Washington (CNN)Now that the White House and Capitol Hill are unified under Republican control for the first time in a decade, President-elect Donald Trump is promising swift action on a sweeping policy agenda.
Trump's agenda faces new test: GOP leaders in Congress
But walking the line between cooperation with Congress and consistency with campaign promises is no easy task.
"Transitions are such perilous times, in the words of [former Harvard Professor] Richard Neustadt, because they are times of maximum ignorance paired with maximum arrogance," said Russell L. Riley, author of "Inside the Clinton White House: An Oral History."
During his improbable journey from reality TV star to President-elect, Trump broke with members of his own party on a variety of issues ranging from immigration to trade, from protecting seniors to cleaning up Washington.
Now, like Bill Clinton in 1993, George W. Bush in 2001 and Barack Obama in 2009, Trump enters office with his party in control of both the House and Senate. But that doesn't guarantee smooth sailing.
Bill Clinton, for instance, fashioned an independent political identity during his 1992 campaign and was quickly tested after his election, noted Riley, the co-chair of the Miller Center's oral history program at the University of Virginia.
Following his victory, Clinton had dinner in Little Rock with the Democratic congressional leaders of his day: Tom Foley, George Mitchell, and Dick Gephardt. Clinton's goal was to win their support for reducing the deficit, overhauling health care, and enacting family and medical leave. They happily agreed.
But the barons of the Beltway had an agenda of their own: they wanted Clinton to put two of his signature issues on the back-burner: welfare and political reform.
During his campaign, Clinton had called for the line-item veto, campaign finance reform, and significant reductions in Capitol Hill staff. He also had called for "ending welfare as we know it" -- a key issue for branding himself as a New Democrat.
Despite the promises he made on the campaign trail, congressional leaders persuaded Clinton that political and welfare reform should take a backseat.
"Bill Clinton thought it was important to offer some concessions up front. He thought they would offer compromises over time," said David Gergen, a senior CNN political analyst who served as an adviser to four presidents including Clinton. The congressional leaders came away thinking, "This is a guy we can push around."
In the view of former Commerce Secretary Mickey Kantor, the concessions Clinton made on political and welfare reform left him looking like a "typical liberal Democrat" during the first two years of his presidency, helping to set the stage for the 1994 Republican takeover of Congress.
Throughout his campaign, Trump presented a vision of "America first" economic nationalism that put him at odds not only with Democrats but also with his fellow Republicans.
There are already signs that Trump is backing away from two of his most inflammatory positions that could ease relations with Republican leaders.
In an interview with The Wall Street Journal, Trump deflected when asked if he would make good on his promise to appoint a special prosecutor to investigate Hillary Clinton for her use of a private email server while she was secretary of state.
"It's not something I've given a lot of thought, because I want to solve health care, jobs, border control, tax reform," said Trump.
Trump's team also took steps during the campaign to diffuse the conflict over his call last December for a "total and complete" shutdown on Muslims entering the United States by morphing his religion-based test into a more nuanced pledge to "suspend immigration from terror-prone regions where vetting cannot safely occur."
But even as he re-calibrates those two positions, Trump will still come under scrutiny for how closely he adheres to five promises that separated him from Senate Majority Leader Mitch McConnell, House Speaker Paul Ryan and other GOP leaders.
Trump's pledge to "build a wall" between the United States and Mexico might be the most oft-repeated campaign promise in recent American history.
"On day one, we will begin working on an impenetrable, physical, tall, powerful, beautiful southern border wall," said Trump on August 31 in one variation of his speech.
But there are already signs that Republican leaders want to duck the issue.
Asked three times on Wednesday by CNN if he supports Trump's signature plan to build a wall, McConnell would only say: "I want to achieve border security the way that's most effective."
For his part, Ryan said after the election that he sees the need for some kind of "physical barriers on the border" but he said he would "defer to the experts" on the right way to secure the border.
Last year, Trump called for setting up a deportation force to remove all 11 million undocumented immigrants currently in the United States.
Later on in the campaign, Trump changed his focus to "criminals." Sunday on CBS' "60 Minutes," Trump said he is now focused on deporting or incarcerating the undocumented immigrants who are drug dealers or gang members -- a group that Trump estimates includes 2 to 3 million people.
For now, congressional leaders are doing their best to paper over their differences with Trump on immigration by saying they are focused on border security.
Ryan said this week the US must come up with a solution that does not involve mass deportation.
"We are not erecting a deportation force," Ryan told CNN's "State of the Union with Jake Tapper" on Sunday.
But down the line, Republicans will be faced with the question of what to do with the larger group of 11 million undocumented immigrants currently in the United States who have not committed serious crimes while being here.
During the campaign, Trump ruled out a pathway to legal status for this group if they do not first leave the United States.
"There's no path to legalization unless they leave the country," Trump told CNN's Anderson Cooper on August 26. "When they come back in, then they can start paying taxes, but there is no path to legalization unless they leave the country and then come back."
This position puts Trump at odds with Ryan, who supports a path to legal status without having to first leave the United States.
"I'm a person who believes that for the undocumented, we have to come up with a solution that doesn't involve mass deportation, that involves people the opportunity to get right with the law, to come in and earn a legal status while we fix the rest of legal immigration," Ryan said at an April 27 town hall sponsored by Georgetown University's Institute of Politics and Public Service.
Trump has changed stances over the years on a range of issues -- everything from guns to abortion to health care.
But one area where Trump has been consistent since he emerged on the national scene in the 1980s is his belief that US trade deals have undermined American workers and put the country at a competitive disadvantage.
On day one of his administration, Trump has promised to: (1) renegotiate -- or even withdraw -- from NAFTA; (2) to withdraw from the Trans Pacific Partnership; and (3) to direct his secretary of the Treasury to label China a currency manipulator.
In his first 100 days, Trump has promised to pursue legislation he refers to as the "End the Offshoring Act" that would establish tariffs to discourage companies from laying off workers and relocating overseas.
But Ryan will not commit to passing tariffs.
The "smarter way" to help workers is "fixing" the US tax code "not tariffs, not trade wars," Ryan said on "State of the Union" Sunday.
Ryan's "Better Way" agenda calls for implementing a "destination-basis tax system" that would exempt exports and tax imports.
"There are better ways of dealing with making American products and workers more competitive," said Ryan. "And really, that's fixing our tax code."
Another area where Trump broke from GOP orthodoxy is on the nation's entitlement programs for older Americans.
"[Ryan] wants to knock Medicare way down ... I'm not going to cut it, and I'm not going to raise ages, and I'm not going to do all of the things that they want to do," Trump told WROK radio back in March.
"They want to cut it very substantially -- the Republicans -- and I'm not going to do that," Trump added, referring to Medicare and Social Security.
Ryan's policy blueprint, however, calls for gradually raising the Medicare eligibility age from 65 to 67 beginning in 2020. It also calls for capping overall government spending on the program that could make seniors financially liable for future cost growth.
It would also transform Medicare into what Ryan calls "a fully competitive market-based model known as premium support." Traditional Medicare would compete directly with health plans offered by private insurance companies.
In a sign that Trump might be moving in Ryan's direction on Medicare, the President-elect's new transition website -- GreatAgain.gov -- says: "modernize Medicare, so that it will be ready for the challenges with the coming retirement of the Baby Boom generation -- and beyond."
In the middle of October, following the release of the "Access Hollywood" tape when many in the media had already written off his chances, Trump proposed a package of reforms to "drain the swamp in Washington" -- everything from congressional term limits to new restrictions on White House and congressional officials becoming lobbyists.
In his "Contract with the American Voter," Trump promised quick action.
"On the first day of my term of office," the contract read, "my administration will immediately ... propose a constitutional amendment to impose term limits on all members of Congress."
McConnell, one day after the election, said term limits would be a non-starter in the Senate.
"It will not be on the agenda in the Senate," said McConnell. "I would say we have term limits now -- they're called elections."
But despite McConnell's opposition, Trump renewed his push for amending the Constitution to include congressional term limits during a Sunday interview with CBS' "60 Minutes."
"We're going to put on term limits, which a lot of people aren't happy about, but we're putting on term limits," said Trump. "We're doing a lot of things to clean up the system."