Majority Leader Mitch McConnell (R-Ky.) said Tuesday that control of the Senate is a coin-toss contest that could end his six-year reign over the chamber, even after the successful confirmation of Supreme Court Justice Amy Coney Barrett that conservatives hoped would rally the base for GOP senators.

McConnell remained bullish that the nomination process helped Republican incumbents in some of the more traditionally conservative states, but he acknowledged that liberal donors to an online portal have expanded the map to give Democrats more paths toward winning the majority.

“I think it’s a 50-50 proposition,” McConnell said during a telephone interview with The Washington Post. “You know, the other side has done a great job with ActBlue. We always knew we were going to have spirited races in Montana, Colorado, Arizona, Iowa, North Carolina and Maine. They’ve been able to make it competitive in Kansas, Georgia, South Carolina and Alaska.”

McConnell’s assessment came a few days after President Trump, in a private meeting with donors, said it will be “very tough” for Republicans to keep control of the Senate because he cannot support some of the party’s candidates.

In the previous two election seasons, Supreme Court vacancies played into McConnell’s personal legacy — moving federal courts to the right — and the broader political climate for Republicans. When McConnell refused to allow President Barack Obama’s nominee to receive even a hearing for eight months in 2016, the move helped galvanize conservatives to vote for President Trump and GOP incumbents. Two years later, Justice Brett M. Kavanaugh’s confirmation clash also revved up conservative voters and helped McConnell expand his majority by two seats while Republicans got crushed in other races.

When an aide relayed the news of Justice Ruth Bader Ginsburg’s death on Sept. 18, McConnell was less certain that the fight would create the same boost this time.

“I didn’t believe it would be a negative; it certainly was a positive in 2016 and a positive in 2018. So I didn’t think it would be a negative. I didn’t know for sure whether it would be a positive,” he said.

Democrats contend that the nomination did not do much to shore up support for embattled Republican incumbents, conceding only that in the most conservative states it could have some benefit. Instead they point to a surge in donations during the last 12 days of September to Democratic challengers and the continued energy this month.

That has allowed Democrats in places like Georgia and Kansas to spend far more than veteran incumbents, making Republicans reliant on unlimited multimillion-dollar donations from a few big contributors to McConnell’s friendly super PAC.

But McConnell dismissed that liberal energy. “That was already there,” he said, suggesting that activists were pushing earlier this year for liberal policies such as expanding the size of the Supreme Court and abolishing the filibuster. “All of that predated the death of Justice Ginsburg.”

Regardless of how the politics played out, McConnell started preparing in the spring to move quickly if a vacancy occurred on the Supreme Court.

He began making clear that he would fill any vacancy and started citing a little-noticed comment he made almost two weeks after Justice Antonin Scalia’s death in February 2016: If he and the president were of the same party, he would confirm a justice no matter how close to the election.

McConnell and aides drafted possible statements Aug. 13 for a potential vacancy, even without any retirement announcements or imminent signs of Ginsburg’s health deteriorating, according to a senior GOP aide familiar with the planning, who spoke on the condition of anonymity to talk about the closed-door discussions.

McConnell already had his mind set on Barrett by early September, when Trump released a new list of potential justices.

And the day after Ginsburg died, McConnell told Trump’s top advisers that Barrett was “the obvious choice.” In further discussions, including with the president, McConnell balked at suggestions of other female jurists who came from swing states and who might provide more political impact in November, according to the GOP aide.

He believed that Barrett was the easiest to confirm, having had a high-profile nomination to the U.S. Court of Appeals for the 7th Circuit in 2017, and his only remaining question was whether they could finish the confirmation before the election without violating too many norms of the process.

“Once I knew that, Lindsey and I sat down and worked out a flow chart that brought us to where we were last night,” he said of Sen. Lindsey O. Graham (R-S.C.), chairman of the Senate Judiciary Committee. Barrett was sworn in Monday evening.

At one month from nomination to confirmation, Barrett moved faster than any Supreme Court nominee in almost 45 years.

McConnell made clear that he thought finishing before Election Day would be the best way to help GOP candidates. “I think the advantage of going ahead was the American people could take it into account in the election,” he said.

Most Republican strategists believed that a court battle would turn the Senate races into more traditional partisan contests, helping in the handful of states where Trump won by a comfortable margin four years ago.

But the confirmation fight probably did not help Republican Sens. Susan Collins (Maine) and Cory Gardner (Colo.), both in states where Trump is trailing Democrat Joe Biden significantly in public polling.

With Republicans playing defense in 12 states and Democrats defending just two seats, McConnell could not afford to worry about one individual race.

“It’s pretty hard to calculate the politics of this when you’ve got as many different states up. I mean, look, we’ve got all kinds of challenges in different kinds of states,” he said.

He pointed to Montana, which Trump won by 20 percentage points four years ago, as a place where the incumbent, Sen. Steve Daines (R), has benefited because his opponent, Gov. Steve Bullock (D), has supported expanding the size of the Supreme Court.

McConnell views that issue as key to saving the Senate majority.

“It’s certainly been a plus and allowed us to talk about court-packing in a way that seemed just a hypothetical before this Supreme Court nomination came up,” he said.

In recent speeches, McConnell has said that pushing the federal courts toward conservative views was more important than passing legislation.

“No tax bill is permanent beyond the next election. In other words, you know, majorities come, majorities go,” he said in the interview.

But lifetime judicial appointments are the closest thing to a permanent legacy.

A week after Trump won in 2016, McConnell said, he called Donald McGahn, the first White House counsel, who shaped the entire judicial selection process. A University of Notre Dame alumnus, McGahn found Barrett at his alma mater’s law school and advanced her name to the Senate for her 2017 circuit court nomination.

It’s unclear whether voters will reward Republicans for Trump’s third Supreme Court justice or if they will discount it as something that has already been achieved — and whether, instead, the fight further energized anti-Trump forces.

Even if he loses the majority, McConnell said, his four years of work on this issue will outweigh his previous 32 years in the Senate.

“It was entirely premeditated,” he said. “And my thought was, it was the closest thing we could possibly do to have a permanent, positive impact on the country, right of center.”