Washington (CNN) -- It's become a familiar pattern in Washington.
A new controversy emerges. Media reports raise questions, and Republican critics hurl accusations. President Barack Obama stays hidden from scrutiny, leaving spokesman Jay Carney to bob and weave like a cornered boxer in the White House briefing room.
Only under heightened public anger and political pressure does Obama emerge, such as Wednesday's hastily arranged news conference intended to tamp down a growing uproar over allegations of sometimes deadly waits for care at Veterans Affairs hospitals.
The result? A growing perception of a White House under siege as Obama's presidency approaches its two-thirds mark, struggling with a litany of problems that overwhelm any administration successes.
Some involve serious missteps, like the dysfunctional Obamacare website last fall that temporarily undermined progress on the President's signature achievement.
Others are more politically contrived controversies made more prominent in an election year, such as Republican hounding over the 2012 Benghazi terrorist attack and IRS targeting of groups seeking tax exempt status.
The GOP seeks to portray Obama as ineffective and even negligent, with Senate Republican leader Mitch McConnell complaining Thursday that "the most powerful man in the free world always seems to be the last to know about what's going on in his own administration."
Meanwhile, Democratic colleagues who face tough congressional elections in November distance themselves from a President with negative approval ratings.
Here are the major controversies that have confronted the Obama administration, with a look at how we got here and what they mean:
Veterans Affairs: A long-time problem getting worse
As a U.S. senator, Obama sat on the Veterans' Affairs Committee and campaigned for president on resolving problems faced by returning soldiers.
Now he finds himself under heavy criticism for what critics call a delayed and weak response to excessive and sometimes deadly waits for care at VA hospitals and alleged practices to cover them up, as uncovered by a CNN investigation.
The VA has acknowledged 23 deaths in several states due to delays in care, and sources told CNN that as many as 40 veterans died under similar circumstances in Phoenix.
Such problems touch on an emotional topic -- caring for America's military veterans, many of whom served in war -- and the revelations of scheduling tricks and secret lists to hide months-long waits sparked outrage across the political spectrum.
So far, Obama ordered his deputy chief of staff, Rob Nabors, to review what was happening at the VA. Robert Petzel, a VA undersecretary for health care, was forced out shortly before his planned retirement this year, and the department's inspector general has launched an independent investigation.
Republicans, veterans groups and some Democrats say that's not enough, with increasing calls for Obama to fire Veterans Affairs Secretary Eric Shinseki as part of a broad housecleaning.
In his first public remarks on the matter in weeks, Obama on Wednesday continued to back Shinseki while promising punishment for any proven misconduct. Wait until we have the facts before deciding on how to proceed, he urged.
Obama noted his administration's efforts to provide veterans with expanded services, access to education and help finding jobs, but his remarks disappointed critics.
The American Legion called Obama's decision to keep Shinseki in office "unfortunate," while Republican leaders said the President must address systemic problems at VA that involve much more than the possible removal of the Cabinet secretary.
"The general can leave and we can wait around for months to go through a nomination process and we get a new person, but the disaster continues," House Speaker John Boehner told reporters on Thursday.
The GOP-led House passed a bill giving Shinseki greater authority to fire top managers, and some in Congress urged Obama to delegate such power by executive action to speed the process.
Republican Sen. Marco Rubio of Florida, who pushed Thursday for an immediate Senate vote on the House measure, said: "I don't think that any of us want to go home for the Memorial Day recess and when we are asked `what are you doing on this issue?' our answer is `well, in about 15 days we are going to have a hearing on this crisis.'"
Obamacare: the GOP's boogeyman
Socialism! Death panels!
For four years, Republicans mustered unrelenting and vitriolic attacks on Obama's signature health care legislation that passed with no GOP votes in 2010.
From presidential nominee Mitt Romney on down, Republicans made repeal of the Affordable Care Act a major issue of the 2012 election and continued efforts to undermine its implementation even after Obama won a second term.
The GOP efforts appeared increasingly negligible until the Obamacare website meltdown.
What should have been the crowning moment of the reform process -- the October 1, 2013, rollout of exchanges for uninsured people to buy newly affordable health coverage -- became a full-blown crisis when the government website didn't work.
Republican critics regained their vigor, insisting the episode showed the Obamacare reforms as a whole didn't work. Carney came under withering questioning, while Obama dispatched a top White House aide to get the website functioning properly.
The President also backed Health Secretary Kathleen Sebelius, the administration's focal point for implementing the reforms, at least until the website got working again and the sign-up period concluded at the end of March with enrollment exceeding goals.
Then Sebelius stepped down.
Benghazi: A "twofer" for Republicans
A tragedy in which four Americans died in a terrorist attack now symbolizes the political dysfunction in Washington.
In the midst of the 2012 presidential election, the assault on a U.S. compound in Benghazi, Libya, became a campaign flashpoint.
Obama was running on foreign policy credentials burnished by the mission that killed Osama bin Laden, boasting al Qaeda was "on the run."
His administration initially blamed the Benghazi attack on a spontaneous protest over an anti-Muslim video made in the United States, rather than the seemingly planned assault by well-armed terrorists, some with al Qaeda affiliations.
Republicans led by Romney immediately accused the Obama administration of misleading the public on what happened to hide a major security breakdown that signaled the broader failed policy in the region.
A special review board set up by then-Secretary of State Hillary Clinton determined flaws in security planning and made recommendations adopted by the State Department.
However, neither the review board nor multiple investigations by congressional committees uncovered the kind of damaging revelation sought by Republicans to hurt both Obama and Clinton, the overwhelming favorite for the Democratic presidential nomination in 2016 if she decides to run.
Now, House Republicans have formed a new select committee to keep public focus on an issue that resonates with conservatives ahead of the November congressional elections. The special investigative panel also offers a continuing attack route against Clinton, with expectations she will be called to testify.
Democrats initially balked at being part of the select committee, but House Minority Leader Nancy Pelosi on Wednesday named five members to join seven Republicans on the panel.
IRS: An easy target
Everybody hates the tax collector, and revelations of political targeting by the Internal Revenue Service gave conservatives even more reason to pile on.
Republicans have tried to maintain public focus on the evolving IRS targeting scandal, inferring it could reach to the top levels of the Obama administration.
No evidence so far from several congressional investigations has revealed direct political motivation or any involvement from outside the IRS. Both liberal and conservative groups were flagged when assessing their eligibility for a tax break available to social welfare organizations.
However, only conservative groups faced delayed processing and inappropriate questioning about political activity that would make them ineligible, according to IRS officials.
The focus on tea party affiliated groups stoked conservative anger and a GOP talking point that lumps the controversy with others during the Obama presidency.
"From the Obama administration's IRS scandal, to its Obamacare website fiasco, just about every time the president claims to be in the dark until the wrongdoing surfaces on its own usually in the press," McConnell said Thursday.
Ukraine: measured response labeled weakness
It all happened so fast -- a Russian incursion in February that seized control of Ukraine's Crimea peninsula.
The expansionist move by Russian President Vladimir Putin immediately set up a "Russia versus the West" showdown, pitting Moscow against the United States and its European allies.
Preceding all that was a veritable coup in Ukraine driven by pro-European populism that ousted the pro-Russian prime minister. Putin acted amid the political chaos in the former Soviet satellite to annex Crimea, which has a majority ethnic Russian population and hosts Russia's vital Black Sea fleet.
Despite calls by conservatives for arming Ukraine, Obama acted in concert with NATO allies in Europe, imposing sanctions but ruling out a military response over Crimea.
However, he and his NATO counterparts declared they would uphold their treaty obligation to protect any alliance member from a similar Russian push, and they boosted military exercises in the region.
No matter the foreign policy issue, Obama comes under criticism for policies that seek to reduce the U.S. military footprint abroad and promote collaboration with allies instead of the American "first in" approach of the past.
Longtime foes such as Republican Sens. John McCain of Arizona and Lindsey Graham of South Carolina complain such a measured response weakens the nation's standing in the world.
Obama argues his way avoids mistakes such as leaping into a war in Iraq over the false perception that Saddam Hussein possessed weapons of mass destruction.
"Why is it that everybody is so eager to use military force after we've just gone through a decade of war at enormous costs to our troops and to our budget?" he asked during a trip to Asia last month. His approach may not bring dynamic results, he added, "but we steadily advance the interests of the American people and our partnerships with folks around the world."
Syria: Whose red line?
If Obama regrets anything, it is probably his declaration in 2012 that the Syrian government's use of chemical weapons against its own people would cross a "red line" for a U.S. military response.
The phrase has become synonymous with empty threats, and analysts say Obama's failure to follow through on his warning against President Bashar al-Assad's regime undermined confidence by U.S. allies around the world that Washington would have their back in a crisis.
In the end, though, Obama appeared to get what he wanted without putting any U.S. troops at risk, as Syria -- under pressure from ally Russia -- handed over more than 90% of its declared chemical weapons arsenal to the international community.
Talks with Russia and Syria continue on eliminating the rest by a June 30 deadline, a target that analysts believe is unlikely to be met.
Critics contend the President's stance has failed to curb the al-Assad regime or stop the civil war blamed for more than 100,000 deaths. In particular, some lament the lack of a U.S. military response to chemical weapons attacks in Syria last year.
Secretary of State John Kerry argued last month that the U.S. approach emphasizing diplomacy yielded a better result.
"Would you rather drop a few bombs, send a message, and then have him (al-Assad) still with the weapons and capacity to deliver them?" Kerry asked the Senate Foreign Relations Committee he used to chair. "Or would you rather get all of them out?"