WASHINGTON — As an exercise in raw presidential power, it was a flop. As a political tactic, it backfired. And as a coda to his final weeks in office, President Trump’s threat to veto a $900 billion Covid relief and government funding bill merely underscored his tumultuous tenure in the Oval Office.For five days, starting before Christmas, Mr. Trump virtually held the nation hostage, delaying the extension of unemployment benefits for millions of out-of-work Americans, holding up the delivery of $600 checks, and dangling the possibility of a total government shutdown even as officials raced to distribute a coronavirus vaccine.And then he caved.After calling the bill “a disgrace” and mocking the checks as “measly,” the president signed the legislation into law on Sunday night, claiming to have won concessions from Congress in the process, including votes to increase the individual payments to $2,000. But in truth, Mr. Trump achieved little more than a few face-saving pledges that will do nothing to substantially alter the bipartisan legislation.“It’s another example of the story of the Trump presidency,” said Michael Steel, who was press secretary for John Boehner, Republican of Ohio, when Mr. Boehner was speaker of the House. “He achieved a few more days of chaos at the end of a chaotic presidency.”The veto threat was the latest attention-getting maneuver by a president who appears unwilling to accept the reality that Washington is moving on without him. With only 23 days left in his term, Mr. Trump tried — and failed — to wrest back at least the appearance that he is still in control of the nation’s destiny.On Monday, Democrats put the president’s demands to the test in a House vote on increasing the individual stimulus payments to $2,000, an effort intended to either win approval for heftier payments long supported by Democrats or force Republicans to reject them and defy Mr. Trump. The vote just reached the two-thirds majority needed to pass the House, with 44 Republican lawmakers backing the effort.It is unclear whether the Senate will entertain such a measure. Senate Republicans have resisted increasing the payments, citing concerns about the federal budget deficit, and Senator Mitch McConnell, Republican of Kentucky and the majority leader, in a statement on Sunday made no mention of the $2,000 payments or any of the president’s assertions about the next steps for the chamber he controls.Mr. Trump’s threat to scuttle a Covid relief bill that took months for lawmakers to agree on came in typically dramatic fashion: On Dec. 22, the president posted a four-minute video to Twitter in which he breathlessly ridiculed foreign aid spending and other examples of what he called “pork” in a bill that his own Treasury secretary and Republican lawmakers had negotiated with Democrats in Congress.“It really is a disgrace,” he said, citing spending that he had endorsed in his own budget and falsely asserting that the legislation “has almost nothing to do with Covid.”He followed up with days of tweets, demanding that lawmakers “increase payments to the people” and stop the billions of dollars in “pork.” It was a repeat of the cliffhanger that he forced the country to endure in the spring of 2018, when Republican lawmakers succeeded in talking the president down from his threat to veto a $1.3 trillion spending deal.That handholding happened again over the holiday weekend, as two of his closest allies on Capitol Hill, Senator Lindsey Graham of South Carolina and Representative Kevin McCarthy of California, the Republican leader, sought to persuade the president to back down and sign the legislation.Mr. Graham lobbied Mr. Trump in person during a round of golf on Christmas Day at the president’s club in West Palm Beach, Fla. And Mr. McCarthy talked for hours on the phone with Mr. Trump, spending much of Sunday trying to assuage the president’s concerns even as he recovered from elbow surgery, according to officials familiar with the conversations.But while Mr. Trump’s decision to sign the bill avoided the calamity of a government shutdown in the middle of a pandemic that is killing more than 1,000 Americans a day, even Republicans struggled to understand how his veto threat accomplished much that was positive for the president or his party.On a practical level, he got very little.In a statement released after he signed the legislation, Mr. Trump asserted that he was “demanding many rescissions,” a technical term for requests by a president for Congress to allow the administration to cut spending that he determines is no longer necessary.But as Mr. Trump found out when he tried a similar tactic in 2018, it works only if a president can muster bipartisan support. (That year, several Republicans in the Senate voted against a $15 billion rescission request by Mr. Trump.)On Sunday, Representative Nita M. Lowey, Democrat of New York and the chairwoman of the House Appropriations Committee, made it clear that the president’s effort would not succeed.“The House Appropriations Committee has jurisdiction over rescissions, and our Democratic Majority will reject any rescissions submitted by President Trump,” she said in a statement.Mr. Trump said the House and Senate “have agreed to focus strongly on the very substantial voter fraud which took place” in the 2020 election. In fact, the Democratic-run House is certain to ignore that charge. And even in the Senate, there is little appetite to join the president’s voter fraud crusade.Republican leadership this month urged senators on a private call to accept the results of the election and not to join an effort spearheaded by some House Republicans to overturn them.And Congress is unlikely to embrace Mr. Trump’s call to eliminate protections for social media companies. He has argued without evidence that Section 230 enables websites to censor conservative views, but data shows that conservative personalities and publishers often thrive online.While the concerns about Section 230 are bipartisan, it is unlikely that lawmakers could reach an agreement on the issue within the next week. Mr. Trump and his allies have yet to find substantial common ground with Democrats who primarily want changes addressing discriminatory advertising or terrorist content online.Politically, the president’s veto threats served only to put his Republican allies in the House and Senate on the hot seat.In the House, Republicans who were eager to reject $2,000 stimulus checks could not simply ridicule it as an idea cooked up by Speaker Nancy Pelosi, a Democrat, who quickly seized on the president’s words to try to pass a bill that would increase the direct payments. Those who wanted to vote against the larger amount had to buck their own president — and the voters who support him — as well.Representative Kevin Brady of Texas, the top Republican on the Ways and Means Committee, complained on the House floor that the proposal had been “hastily dropped on us at the last minute” and would not assist those who needed it most.“I worry that this whopping $463 billion won’t do what’s needed, stimulate the economy or help workers get back to work,” Mr. Brady said.In the Senate, the president’s five days of grousing served only to confuse the Republican position on direct payments, which had been carefully calibrated with senior members of Mr. Trump’s administration.For months during negotiations, Senate Republicans have resisted increasing the payments above $600, citing concerns about the federal budget deficit. It is unclear whether the Senate will even take up a vote on increasing the size of the checks.Mr. Trump had claimed that “the Senate will start the process for a vote” on $2,000 checks. In the legislative lingo that rules the Senate, that is a far cry from guaranteeing approval of the higher amount.Brendan Buck, a Republican strategist who served as a senior adviser to Paul Ryan of Wisconsin when he was House speaker, said he was deeply skeptical that Republicans would want to take up the president’s cause for higher stimulus payments. And Mr. Buck noted that there was almost no time for that to happen, anyway.“It’s not based in any reality: the substance and the politics and the clock. There’s no chance for that,” he said. “It does feel like he totally caved without getting anything, and it’s unclear to me why.”In four years in the White House, Mr. Trump has had some success in bending Congress to his will. He worked with Republican lawmakers to push through a $1.5 trillion tax cut in 2017. His Republican allies in the Senate have confirmed a record number of federal judges, including three new justices on the Supreme Court.But the threat to veto the Covid relief bill was an ultimately fruitless exercise that will do little to bolster Mr. Trump’s legacy.David McCabe contributed reporting.