Even before he touched off a political firestorm by firing FBI director James Comey on Tuesday, President Trump’s policy agenda was fraying at the edges. Now the prospects of passage of key elements of his agenda seem even worse as Democrats threaten to pose new obstacles to congressional action.

Upon taking office, Trump vowed quick action on his campaign promises, including the repeal and replacement of the Affordable Care Act, a major buildup of the military, the largest tax cut since the Reagan era, a $1 trillion surge in infrastructure spending, and construction of a wall along the southern border that the president insisted Mexico would ultimately pay for.

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Since then, however, sharp divisions within the congressional Republican majority, solid Democratic opposition and economic and budgetary realities have intervened to slow many of those proposals to a crawl.

For instance, it took three tries and nearly four months before Trump and House Speaker Paul Ryan (R-WI) were finally able to pass the GOP’s American Health Care Act in the House last week, only to have Senate Republican leaders dismiss it out of hand and set about drafting a new version more palatable to moderates.

Trump’s advisers unveiled the broad outlines of his corporate and individual tax cut plan late last month, touting what they say would be the biggest tax cut since the Reagan era. But many experts say that while the administration might get a vote on the proposals by the end of the year, deliberations could easily extend into 2018.

Enactment of a trillion-dollar infrastructure program to fix the nation’s crumbling roads and bridges was initially premised on obtaining new tax incentives to encourage private investment. However, there was no mention of it in Trump’s one-page tax reform proposal. Elaine Chao, Secretary of Transportation, told an audience recently that she is more focused now on streamlining cumbersome red tape that drives up the costs of building tunnels and rails than a quick injection of stimulus funding.

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The Republican-controlled Congress turned Trump down cold a week ago when he requested a modest billion-dollar down payment on construction of his border wall as part of a final fiscal 2017 spending package to keep the government operating through Sept. 30. While Trump insists that he will ultimately prevail in his drive to build a wall estimated to cost more than $25 billion, he is likely to encounter resistance from members of both parties when he seeks a much larger appropriations for the wall in fiscal 2018.

Now the pugnacious president who has courted controversy by repeatedly denigrating FBI and congressional probes of possible collusion between Trump’s campaign organization and the Russian government during the 2016 presidential campaign has stirred a hornet’s nest of protests from both parties over his firing of Comey.

Trump said he fired Comey on the recommendation of senior Justice Department officials who concluded he had mishandled the investigation of Hillary Clinton’s emails. But Democrats charge that was a pretext for the president to fire the very man leading a growing FBI counterintelligence probe to determine whether Trump associates may have coordinated with Russian hackers to interfere with the outcome of the election.

“It obviously doesn’t help,” said Whit Ayres, a veteran GOP pollster and campaign adviser. “How much it hurts depends upon how the story plays out over the next few weeks. A lot of it is going to depend on whether a special prosecutor gets named and who he names as the next director of the FBI. So it’s really too early to make that judgement.”

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“I don’t think what we’ve seen so far will have any significant effect on his political support,” Ayres added. “His supporters voted for him to shake up Washington, and this is a snap shot of what shaking up Washington looks like … But it’s not too early to say that it makes accomplishing things on his agenda more difficult.”

Ross Baker, a Rutgers University political scientist and congressional scholar, said that Trump already was facing problems in the Senate over the health care legislation, especially with more moderate Republicans like Sens. Rob Portman of Ohio, Shelly Moore Capito of West Virginia and Susan Collins of Maine over preserving expanded Medicaid and funding Planned Parenthood.

Baker said the controversy over Comey’s firing creates a “much more complicated field of play” in which the two parties are more inclined to draw sharper political lines. “Anything that fuels both complications and the possibility of polarization in the mix is bound to have a toxic effect,” he said. “It creates one more battle line in which both sides are particularly well entrenched.”

Those battle lines were in sharp relief late Tuesday evening and Wednesday morning when Democrats threatened to slow the Senate to a crawl unless the Justice Department appointed a special counsel to conduct an independent investigation of possible Trump campaign ties to the Russians.

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“We clearly have the option of slowing down the proceedings of the Senate if there’s not a proper response from the Republicans,” Sen. Chris Murphy (D-CT) told reporters Wednesday morning after a closed-door Democratic caucus meeting that focused on Comey's firing.

Trump and Senate Majority Leader Mitch McConnell (R-KY) have for months bitterly complained about Democratic tactics in slowing consideration of Trump’s cabinet nominees and taking up legislation in committee or on the floor.

On Wednesday, Sen. Richard Durban of Illinois, the No. 2 Democrat in the party’s leadership, objected to the Senate GOP's routine request to allow 13 committee hearings to take place, according to The Hill.