President Donald Trump wasted little time in trying to make good on his campaign pledge to slash government spending to make room for his initiatives, beginning with an executive order issued Monday morning freezing hiring in the federal workforce except in the military.

But Trump may be on a collision course with key Republicans on Capitol Hill over his drive to simultaneously cut fat from the government and reduce the deficit while promoting an ambitious agenda of new spending and tax cuts. Many of the programs Trump’s advisers are targeting have long enjoyed bipartisan support in Congress.

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Even before the billionaire businessman was sworn in as the 45th president last Friday, Trump’s budgetary transition team reportedly began working with the conservative Heritage Foundation on the group’s wish list of major cuts in departments including Commerce, Energy, Justice and State, and the elimination of long-standing programs including the National Endowment for the Arts and the National Endowment for the Humanities.

Heritage recently unveiled a blueprint for achieving a balanced budget necessitating nearly $10 trillion in cuts and savings over the coming decade. Trump, apparently, is eagerly embracing the spending cut road map – especially deep cuts in non-defense domestic discretionary spending, according to The Hill.

White House press secretary Sean Spicer said today that members of Trump “landing teams” met with department and agency officials before the inauguration and talked about ways to create greater efficiencies, eliminate duplication and maximize federal tax dollars.

“It’s more a question instead of cutting, it’s about how do we spend and respect the Americans’ taxpayer dollars more going forward,” Spicer told reporters at the White House in discussing proposed spending cuts and the federal employee hiring freeze. “There’s been frankly some degree of lack of respect for taxpayers’ dollars in this town for a long time.”

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“And I think what the president is showing through the hiring freeze, first and foremost today, is that we’ve got to respect the American taxpayers,” Spicer added. “They are sending us a ton of money ... and to see money wasted in Washington on a job that is duplicative is insulting to the hard work they do to pay their taxes.”

Spicer didn’t highlight specific cuts the new administration has in mind – or confirm a goal of $10 trillion in cuts over the coming decade. Nor did he reconcile the administration’s drive to slash spending with Trump’s ballyhooed agenda that will substantially add to the deficit.

That includes $7 trillion or more in tax cuts, construction of a costly wall along the U.S.-Mexico border, a massive buildup of defense and the U.S. nuclear arsenal, $1 trillion of highway, bridge and other infrastructure projects, and government subsidies for paid family leave, just to name a few.

If Rep. Mick Mulvaney (R-S.C.), Trump’s choice to head the Office of Management and Budget (OMB), survives his Senate confirmation hearings beginning on Tuesday, the fiscal conservative may have a tough time reconciling some of the more glaring contradictions in Trump’s fiscal strategy while the national debt fast approaches $20 trillion.

Mulvaney will likely be grilled by Senate Budget Committee Democrats about his failure to pay $15,000 in payroll taxes for a household employee. But he may encounter even more difficult questions about how he will make the numbers in Trump’s budget add up.

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“There seems to be a hell of a lot on the table, and it’s not just in discretionary spending,” Jim Dyer, a former Republican chief of staff of the House Appropriations Committee, said in an interview Monday. “I am stricken by the sheer volume of stuff that has been thrown out there.”

Dyer warns that the new Trump administration will soon experience fiscal circuit overload, as it tries to balance its major challenges of new tax and trade policies, infrastructure construction and rewriting of the nation’s health care laws with more small-bore concerns of conservative activists such as doing away with the National Endowment for the Humanities or the Legal Services Corporation, an agency that provides financial support for civil legal aid to low-income people.

He continued, “You only have so much political capital, and it seems to me that if I were at the White House I would be investing all of my political capital in taxes, trade, infrastructure and social safety net.”

Trump and his advisers have been counting on an extended honeymoon with House and Senate Republican lawmakers, as they drive to repeal the Affordable Care Act early in the year and complete work on spending bills for fiscal 2017 that runs through next Sept. 30.

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House Speaker Paul Ryan (R-WI) and Senate Majority Leader Mitch McConnell (R-KY) pushed through a short-term extension of spending authority through late March to allow Trump and his budget advisers to have more input in funding the government through the remainder of the fiscal year. “I think the new, incoming government would like to have a say-so on how spending is allocated," Ryan said at the time.

However, The Hill reported today that Trump may be headed for a tough fight with Republican lawmakers – especially veteran members of the Senate—over his plans for deep cuts in federal programs and agencies.

Programs like legal services, essential air service for remote parts of the country including Alaska, and the endowment for the humanities and for the arts all have strong backing on Capitol Hill in both parties and have weathered previous GOP efforts to gut them.

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“I think that would be hard thing to do,” Senate Finance Committee Chair Orrin Hatch (R-UT), said of any attempt to kill legal services, despite the projected savings of $400 million next year. “Even if you wanted to do that, you couldn’t get it through the Senate,” he said.

Sen. Lisa Murkowski, a senior Republican from Alaska, told the newspaper that she would lead a vigorous battle against any effort to cut funding for essential air service. “It would basically shut down rural Alaska,” she said. “If there is discussion about that, we as the Alaska delegation really have to ramp it up and let people know how critical it is.”