WASHINGTON — In a stark reversal of the position he took in 2016, Sen. Pat Toomey (R., Pa.) said Tuesday that he will support filling a vacant seat on the U.S. Supreme Court this year, despite a presidential election being only weeks away.

Toomey, who in 2016 argued that the Senate should wait months for the results of that year’s presidential election because the ideological balance of the court was at stake, said the Senate should do the opposite this year because the White House and Senate are controlled by the same party.

“The important difference between now and 2016 is the difference in the political configuration. That’s what’s different,” Toomey said in a telephone interview after announcing his position. “When one party has the White House and the Senate, there’s no division, the American people have put that party in charge, and when a vacancy occurs, precedent and the arguments from both Democrats and Republicans has been consistent with going ahead and confirming [a justice]."

Toomey’s announcement on the highly emotional and consequential debate came after Senate Republicans appeared to have already solidified the votes they need to move ahead in replacing the liberal Justice Ruth Bader Ginsburg with a conservative nominated by President Donald Trump. If they succeed in filling the seat held by Ginsburg, a progressive icon who died Friday, Republicans will likely shift the balance of the court rightward for years to come.

The outcome could have tremendous ramifications on a wide range of American life. The court is already slated to take up key cases dealing with abortion laws and the Affordable Care Act in the coming weeks. Other major rulings in the last decade have shaped laws on health care, same-sex marriage, voting laws, and the flow of money into politics.

Toomey issued his statement Tuesday hours after Sen. Mitt Romney (R., Utah) said he would also support moving forward with a confirmation vote this year, effectively ending any questions about whether the GOP would have the support needed to do so.

It would take four Senate Republican defections to stop Trump and Senate Majority Leader Mitch McConnell from pushing through a Supreme Court confirmation this year, and only two GOP senators have said they would oppose the move.

“Pat Toomey is the spineless lapdog of Donald Trump and all of his big money friends,” Brendan Welch, a spokesperson for the Pennsylvania Democratic Party, said in a statement. “The people of Pennsylvania deserve a Senator who will fight for them and tell them the truth. Pat Toomey is clearly not that guy.”

In 2016, Toomey took a sharply different stand when the political roles were reversed. At the time, he opposed a Senate confirmation vote on Judge Merrick Garland, who was nominated to the high court by President Barack Obama, eight months before that year’s election.

Garland would have replaced a towering judicial conservative, the late Justice Antonin Scalia, but Toomey argued that before changing the political balance of the court, voters should have a say by choosing the president who would fill the seat.

“With the U.S. Supreme Court’s balance at stake, and with a presidential election fewer than eight months away, it is wise to give the American people a more direct voice in the selection and confirmation of the next justice,” Toomey said in a March 2016 statement.

That same month, he wrote to a constituent expanding on his thoughts.

“The vacancy created by Justice Scalia’s passing is especially sensitive because it will fundamentally affect the balance of the Supreme Court for a generation or more,” Toomey wrote to Nancy McKittrick, of Montgomery County, who shared the letter with The Inquirer this week. “Given that we are already well into the presidential election process and that the Supreme Court appointment is for a lifetime, it makes sense to give the American people a more direct say in this critical decision.”

The letter also noted that the power to fill Supreme Court seats is shared between the president and Senate.

Toomey joined fellow Republicans in a blockade that prevented Garland from receiving so much as a Senate hearing. Trump won the election and eventually named Scalia’s replacement, Neil Gorsuch, maintaining a 5-4 conservative majority on the court, and leaving another lasting mark in the country’s bitter fight over the judiciary.

Now, Trump is poised to replace Ginsburg and give the court a 6-3 conservative lean — a more lopsided advantage than liberals would have enjoyed had Garland been confirmed.

Toomey, in the interview, argued that the court’s balance isn’t changing because it is, and would remain, conservative.

Toomey joined fellow Republicans in arguing that this year is different because both the White House and Senate are now controlled by the same party and that Democrats would do the same thing if they had the chance.

He and other Republicans accused Democrats of their own hypocrisy, noting that Democrats in 2016 urged the Senate to fill the vacant court seat, even in an election year.

“Are we now supposed to operate by two different sets of rules that systematically advantage the Democrats?” he asked in a statement earlier Tuesday.

Those Democratic calls, however, came months, not weeks, before an election, and before Republicans set a new modern precedent of blocking a nomination because of a looming election.

Toomey’s statement also pointed out that in 2016, he told the Associated Press he would handle each election-year vacancy as it arose.

His stance is sure to draw scorn from Pennsylvania liberals who have turned him into a top political target ever since the 2016 election, accusing him of hewing too closely to Trump after promising to be an “independent voice” during his reelection campaign that year.

But there was also political risk for Toomey in bucking the president, who has a fervent political base that relishes his successes. Toomey will likely have to face Republican primary voters in 2022, whether he seeks reelection or runs for governor, a move he is widely seen as considering. Trump has made his record of installing conservative judges one of his signature appeals to Republicans, and defying the president on a charged Supreme Court nomination could be damaging in a GOP primary.

Already heated court battles have taken on new levels of intensity and acrimony after the Garland blockade and the contentious confirmation of Justice Brett Kavanaugh, who faced unproven accusations of sexual assault, a confrontation that left both parties infuriated.