The traditionally routine exercise took on heightened significance this year after Trump and his allies pressured the board’s two Republicans to reject certification and seek a delay in order to investigate “irregularities” in Detroit’s vote counting — allegations that are not supported by any evidence of wrongdoing. Republicans have also pushed officials in other states to delay certification and have challenged the election results in court, mostly resulting in a string of legal losses.

But with Trump's failure to make inroads in state and local election boards, his options for clinging to power have narrowed dramatically. With little hope of derailing state certifications — which will officially determine which slates of presidential electors cast their votes for president on Dec. 14 — Trump's last line of attack may rely on allies in Congress, who are permitted to challenge the electoral vote count on Jan. 6, when the tally comes before them for certification.

The Michigan certification took on the air of a must-win effort for Trump as the pillars of his legal and political strategy came apart in recent days. Republicans on Capitol Hill have gradually begun calling for him to acknowledge defeat and begin the transition to a Biden presidency. On Monday afternoon, Sen. Lamar Alexander (R-Tenn.), who is leaving Congress in January, urged Trump to exit gracefully.

“Since it seems apparent that Joe Biden will be the president-elect, my hope is that President Trump will take pride in his considerable accomplishments, put the country first and have a prompt and orderly transition to help the new administration succeed," Alexander said. “When you are in public life, people remember the last thing you do.”

Despite the public pressure, one of Michigan’s two Republican board members joined the Democratic board members to certify the state’s election results, tossing aside the president’s attempts to slow the process down in the critical battleground state. Republican Norm Shinkle did not vote to certify the results, instead abstaining, after indicating in interviews that he was not in favor of certification.

But Aaron Van Langevelde, a lawyer for the state legislature’s House GOP caucus, joined Democrats Jeannette Bradshaw and Julie Matuzak in certifying the results. Van Langevelde argued at the meeting that state law requires the board certify results, and it didn’t have the authority to demand an audit or otherwise delay the results.

“I’ve reviewed the law here. It's not complicated, it is very simple,” Van Langevelde said during a back-and-forth with Charlie Spies, an attorney representing Republican John James, who lost to Sen. Gary Peters (D-Mich.) and is also seeking to delay certification. “We’re required to canvass the returns and determine the results.”

Michigan’s certification could be the fatal blow to Trump’s legally dubious efforts to block Biden from attaining the 270 electoral votes he needs to win. Only a few closely contested states remain to be certified, from Pennsylvania to Wisconsin to Arizona, and in each case, there appears to be little energy among Republicans to overturn the will of their voters. The president’s legal cases and the political pressure he’s putting on fellow Republicans to fight the election results are falling flat.

Trump, while vowing to continue to fight, appeared to acknowledge Monday that Biden could be headed to the Oval Office, acknowledging that he green-lighted his GSA Administrator Emily Murphy's decision to begin sharing transition resources with Biden's team.

"Our case STRONGLY continues, we will keep up the good fight, and I believe we will prevail!" Trump tweeted. "Nevertheless, in the best interest of our Country, I am recommending that Emily and her team do what needs to be done with regard to initial protocols, and have told my team to do the same."

In addition to the brushback in Michigan, Trump’s efforts to challenge the vote count or delay certification have so far fallen short in other states Biden carried, including Pennsylvania, Arizona and Georgia.

Trump’s bid to persuade a federal judge to toss millions of votes for Biden in Pennsylvania met with a sharply worded rejection on Saturday. And a small but growing number of House and Senate Republicans in Washington say it’s time for Trump to accept defeat and help smooth the transition to a Biden administration.

“A pressure campaign on state legislators to influence the electoral outcome is not only unprecedented but inconsistent with our democratic process,” said Sen. Lisa Murkowski (R-Alaska) in a Sunday statement. “It is time to begin the full and formal transition process.”

The drama in Michigan came one week after two Republican members of a local canvassing board — in Detroit’s Wayne County — briefly held up certification there, citing mismatches between tabulated totals and various precincts’ poll books. But minor miscalculations are relatively routine, and officials indicated they only affected a tiny fraction of votes, not remotely close to the margin Trump would need to reverse Biden’s large lead in the state. The two Wayne County Republicans ultimately relented, however, sending the decision to the state board.

Republican officials in other states have cast aside Trump’s calls to otherwise delay the inevitable. The most notable example is Georgia, which certified its election results on Friday despite a public pressure campaign targeting GOP Secretary of State Brad Raffensperger, as well as the Republican governor, Brian Kemp. The president and his allies — including both of Georgia’s Republican senators, Kelly Loeffler and David Perdue — attacked Raffensperger by alleging widespread impropriety in the election without actually providing any evidence of it.

Kemp, another steadfast ally of the president, certified Georgia’s Electoral College electors for Biden on Friday as well. He cast his decision as a legal obligation, one that would open up a path for a recount for the president’s team.

On Saturday, the Trump campaign filed for a recount.

Monday is also the deadline for counties to certify their results in Pennsylvania, after which final state certification rests with Secretary of the Commonwealth Kathy Boockvar, an appointee of Democratic Gov. Tom Wolf. Trump’s lawsuit in the state, which was ripped apart by a federal judge on Saturday, sought to block certification. The campaign is currently trying to appeal to the 3rd Circuit Court of Appeals.

Allies of the president — including GOP Rep. Mike Kelly and Sean Parnell, a congressional candidate who lost to Democratic Rep. Conor Lamb — are also trying to block certification in Pennsylvania state court. Their long-shot case argues that the state’s mail voting law, which was passed by a Republican-controlled legislature and was used for elections before November, was unconstitutional.

Across the state, election boards in counties won by both Biden and Trump certified the presidential election results as of Monday afternoon. But in a handful of places, some GOP election officials voted to reject the vote counts — a demonstration of the degree to which Trump’s unsubstantiated claims of fraud have undermined faith in the election.

The most striking example took place in Luzerne County, a historic coal region located in northeastern Pennsylvania. The motion to sign off on the tally passed 3-2, with all of the Democrats on the Board of Elections approving it. Both Republican members voted against certifying the vote in the county, which Trump won by 14 percentage points.

Joyce Dombroski-Gebhardt, a GOP election board member, accused her fellow board members supporting certification of being “guilty of election fraud on the voters.” She told POLITICO last week that she believes Trump won the state.

Keith Gould, another Republican board member, said in the days leading up to Monday that he was undecided and would make a call when he heard citizens' remarks at the election board meeting. During the public comment session, voter after voter asked officials to hold off on the certification process, echoing the groundless claims of Trump and his legal team about widespread election problems. Several voiced conspiracy theories about election software from Dominion Voting Systems. The local GOP county chair and Republican elected officials also implored them to wait to sign off on the vote.

“The board needs to not certify the election until we get more clarity on that whole issue with Dominion,” said GOP Councilman Walter Griffith.

Republican election board members in Allegheny and Montgomery counties, both of which delivered big margins for Biden, also voted against signing off on the vote.

As in Luzerne, they were in the minority and did not affect the approval of the tally.

A small number of counties said they would miss the deadline due to staff shortages and other issues. Counties have signed off late in the past without any problems.

In Arizona, another state that Biden narrowly flipped, the Republican-controlled county board of supervisors in Maricopa County, the state’s most populous county that was critical to Biden’s victory, voted unanimously on Friday to certify its results.

“No matter how you voted, this election was administered with integrity, transparency, and most importantly in accordance with Arizona state laws," Republican Chair Clint Hickman said, rejecting claims of fraud leveled in the state by the president and his team.

Mohave County, which stretches along the state’s northwest border and heavily backed the president, is the only county that has not yet certified its results. Its deadline to certify is by the end of Monday, with the statewide canvass planned for Nov. 30.

Josh Gerstein contributed to this report.