Repealing and replacing Obamacare is within their grasp.
But even with a firm grip on power, Republicans' efforts to make good on that long-running universal campaign pledge are on shaky ground.
If this sounds in any way familiar, well, it should.
The opening volleys of the Trumpcare fight bear some uncanny resemblances to the Obamacare saga, with Republicans stepping in many of the same puddles their Democratic colleagues did back in 2009 and 2010.
Here's a look at some of the similarities:
Obamacare? Trumpcare? Congresscare
President Donald Trump will be the standard-bearer for the law Republicans eventually deliver to his desk. But like Obama and Obamacare, he, too, has outsourced its actual construction to partisan allies on Capitol Hill.
In 2009, the moderate Montana Democrat Sen. Max Baucus took control of the process and steered the bill, which he had workshopped with a bipartisan "Gang of Six" through the Senate Finance Committee over Republican objections.
That bill eventually passed the Senate along party lines, 60-39, but after Republican Scott Brown won a special election to replace the late Sen. Ted Kennedy in January 2010, the Democrats' filibuster-proof majority was broken.
That meant House Democrats, who had previously passed a more progressive bill that included a public option, would have to approve the Senate's, which did not.
House Democrats had to take it or leave it.
The Obama administration stepped up to close the deal. Obama made a hard sell during his State of the Union address, then hosted a White House health care summit
in late February.
After debating, then placating a group of anti-abortion holdouts, then-House Speaker Nancy Pelosi eventually delivered -- without a single GOP defector -- a 219-212 vote to approve the Senate bill.
Days later, Obama would sign into law the reform package that, informally but inescapably, now bears his name. Many of the House members who delivered those difficult votes were swept out in 2010 in a tea party wave from which Democrats have still not recovered.
There were some shadows of these events on Capitol Hill this week when House Speaker Paul Ryan pledged there would be 218 votes -- the bare minimum -- for the first leg of Obamacare repeal.
And Trump warned Republicans, whose consternation at the bill unveiled by GOP elders has since turned to outright rebellion, that they would suffer a "bloodbath" if they vote no.
They, too, can take it or leave it.
Making big changes in a small window
If Kennedy had lived another few years or his would-be elected successor, Martha Coakley, won her special election to the Senate, the bill that landed on Obama's desk in March 2010 might have looked much different.
But with Kennedy's death and Coakley's defeat, Republicans gained a 41st vote in the Senate -- and the ability to filibuster any revisions to the legislation passed on Christmas Eve 2009.
That meant House Democrats would not, as had been initially expected, be able to sit down with their colleagues in the upper chamber and hammer out a compromise bill. If Pelosi's caucus didn't deliver, health care reform was dead.
Republicans have yet to reach a similar fly-or-die moment, but they are working under time constraints. With only 52 votes in the Senate, GOP leadership took steps earlier this year to allow Obamacare repeal to pass with a simple majority through a process called budget reconciliation. Democrats used a similar maneuver to pass some aspects of the original bill.
But if this fiscal year ends without a successful repeal, broader plans to use reconciliation for tax reform -- another high-level priority for the White House and Congress -- would be pushed back again.
As these deadlines approach, expect Trump to amp up the pressure on Republican senators and House members.
The call is coming from inside the House
With Obamacare now under attack from the right, Democrats have mostly set aside their differing ideas about the law and circled the wagons. But in 2009, solidarity seemed a long way off.
In May of that year, protesters in favor of a single-payer national health care program, whose proponents were not invited to testify, repeatedly disrupted a Senate Finance Committee hearing
. They were escorted out of the room on Baucus's order.
In the spring and summer, as Republicans crowded town halls to rail against reform, single-payer advocates agitated from the left. If Hillary Clinton had defeated Trump in November, they would have be in the streets again, pushing for the new Democratic administration to expand coverage.
The Republican bill made public this week has likewise faced serious backlash from elected officials and outside groups. On Capitol Hill, tea party conservatives who want "full repeal" and a small group of senators, concerned about those covered under Obamacare's Medicaid expansion, have suggested they would not support the legislation as it's written.
Groups like the Heritage Foundation, FreedomWorks and the Koch Brothers' Americans for Prosperity have all attacked the bill for not taking drastic enough steps to undo the government mechanisms that support Obamacare.
FreedomWorks on Tuesday night revealed plans to spend big on a digital and social media campaign opposing the Republicans' plan, which they called a "betrayal" and "ObamaCare lite."
Crafted behind closed doors
When Obama was running for the Democratic presidential nomination in 2008, he pledged to put the process on live television.
"That's what I will do in bringing all parties together, not negotiating behind closed doors, but bringing all parties together, and broadcasting those negotiations on C-SPAN so that the American people can see what the choices are," he said during a January 2008 debate with Clinton.
The discussions went forward, but the cameras were mostly absent. Key elements of the law were crafted behind closed doors, leading Republicans to criticize what they described as a secretive and, in some cases, corrupt process.
Vice President Mike Pence, then a congressman from Indiana, lamented negotiators' retreat to "smoke-filled rooms"
as the legislation took shape.
Fast forward eight years and the GOP is facing the same backlash, including from high-profile officials like Sen. Rand Paul. When House Republicans put the replacement bill under lock and key last week, Paul set off -- with cameras in tow -- on a hunt for the mysterious document.
"When we heard it was secret, we wanted to see it even more," he told CNN's Kate Bolduan on Friday. "As we speak, my staff is still going around Washington looking for the bill."
A President making big promises
In the years after Obamacare passed, the former President was repeatedly attacked and lampooned for some of his overly optimistic -- and inaccurate -- public promises.
"If you like your doctor, you'll be able to keep your doctor," Obama said in June 2009, on one of the more than two dozen occasions
he made the pledge. "If you like your health care plan, you'll be able to keep your health care plan."
Like his predecessor, Trump has largely stayed out of the legislative fray while focusing on a more broad public sales job.
"Our wonderful new Healthcare Bill is now out for review and negotiation," he tweeted on Tuesday morning. "ObamaCare is a complete and total disaster - is imploding fast!"
Twelve hours later, after hearing complaints from Republicans, he sought to soothe their worry.
"I feel sure that my friend @RandPaul will come along with the new and great health care program because he knows Obamacare is a disaster!" Trump wrote in the early evening.
But the line that is most likely to follow him through the years came in January, when he declared to The Washington Post
, "We're going to have insurance for everybody ... Much less expensive and much better."