WASHINGTON (AP) — Senate leader Mitch McConnell is the highest-ranking Republican in Congress who has yet to endorse Donald Trump's bid to return to the White House — having once called the defeated president "morally responsible" for the Jan. 6, 2021 Capitol attack.

But that's potentially about to change.

McConnell's political team and Trump's campaign have been in talks over not only a possible endorsement of the former president but a strategy to unite Republicans up and down the party's ticket ahead of the November election, according to a person familiar with the situation and granted anonymity to discuss it.

How, when or where McConnell would endorse Trump is less head-spinning than the idea that it could happen at all: A stunning rapprochement for two men who have not spoken since McConnell enraged Trump by declaring Joe Biden the legitimate winner of the 2020 presidential election.

But a fast-moving series of events ahead of Super Tuesday's elections have been set in motion by McConnell's own sudden announcement he would step down as leader next session and as Trump is on track to move closer toward the GOP nomination.

Taken together, it lays bare the lengths that McConnell, the longest-serving Senate leader and an ever calculating politician, will go as he works to win back Republican control of the Senate in what could be among his final acts in power.

"I still have enough gas in the tank to thoroughly disappoint my critics, and I intend to do so with all the enthusiasm which they have become accustomed," McConnell said last week in announcing his decision to step aside as leader for the next session.

Not long ago, it appeared Trump would have few fans politically lining up behind his bid to return to the White House, particularly from the halls of Congress.

In the aftermath of the Jan. 6, 2021, attack on the Capitol, key Republicans, including McConnell, signaled unequivocally they were done with Trump.

In a scathing speech during the Senate impeachment trial on charges Trump incited the insurrection at the Capitol, McConnell decried Trump's intemperate language and the "entire manufactured atmosphere of looming catastrophe" and "wild myths" about a stolen election.

"The leader of the free world cannot spend weeks thundering that shadowy forces are stealing our country and then feign surprise when people believe him and do reckless things," said McConnell after the mob siege.

Still, McConnell declined to vote to convict Trump of the impeachment charges in the Senate trial, saying it was for the courts to decide, since the defeated president by then was out of office. "He didn't get away with anything yet," McConnell said in the February 2021 speech.

Trump is now charged in several cases including a federal indictment of conspiring to defraud the U.S. and obstruct an official proceeding related to the Jan. 6 attack on the Capitol by supporters trying to stop Congress from certifying the 2020 election. Trump has appealed claiming immunity.

The first sign that McConnell was leaving the door open to reuniting with Trump came in early 2023 when he was asked about Trump's potential return to the presidential campaign. At the time, McConnell suggested he would support the Republican Party's eventual nominee, declining to name names or mention Trump.

But endorsements matter to Trump, who has assigned key campaign staff in charge of roping in support from elected officials in what has become a two-way political street. The GOP leaders are also relying on Trump to support — or at least not attack — their own nominees for the House and Senate.

As McConnell is weighing his decision to endorse Trump despite his concerns over Jan. 6, he is watching core Republican voters flock to the former president. And he is wary of being the one to try to stand in their way.

It's not just McConnell but the other Republican leaders on Capitol Hill who have all quickly fallen in line as Trump emerges ever so close to again becoming the party's nominee at the top of their party ticket this November.

Republican Speaker Mike Johnson traveled to Mar-a-Lago last month to meet with Trump at his private club about House races as the new speaker works to keep his slim GOP House majority.

The other House Republican leaders endorsed Trump as the former president's team pushed for backing ahead of the Iowa, New Hampshire and other early contests. Senate Republican leaders did the same.

And Republican Sen. Steve Daines of Montana, the chairman of the Senate GOP campaign arm who is a friend, hunting and fishing partner to the president's oldest son, Don Trump, Jr., had told others as far back as 2022 he hoped Trump would run again. He became the first member of Senate GOP leadership to endorse him.

When Daines traveled to Mar-a-Lago for his own visit in February 2023, he told Trump the most important thing he could do for Trump was deliver a Senate majority to confirm Cabinet nominees and approve conservative policies, according to another person familiar with the situation and granted anonymity to discuss it. Daines remains close to Trump, and the two speak often, the person said.

"I'm encouraging the Republican Party to unite behind President Trump," Daines said in a recent statement to the media, including AP.

McConnell's past political distaste for Trump appears to be no match for the GOP leader's desire to win back a Senate majority for Republicans one more time as he prepares to exit the leadership stage.

The two have traded harsh words since even before McConnell's 2021 speech, with Trump deriding the now 82-year-old as an "Old Crow."

But in recent weeks Trump has refrained from name-calling McConnell, or using racial slurs against McConnell's wife, Elaine Chao, the former Trump Transportation Secretary, who resigned in the aftermath of the Jan. 6 attack.

While representatives for McConnell and Trump had restarted the conversation, first McConnell had his announcement last week about stepping aside as GOP leader.

Once that project was done, the person said, McConnell's team could turn its attention to this next one.