House Majority Whip James E. Clyburn endorsed former Vice President Joe Biden on Wednesday, becoming the highest ranking congressional Democrat to weigh in on the presidential nominating contest.

Clyburn’s backing of Biden was long expected, but he decided to hold off on a formal endorsement until after the presidential debate Tuesday in his home state of South Carolina. Voters in the state head to the polls Saturday.

[Mitch McConnell tempers GOP enthusiasm for Bernie Sanders]

As he announced the endorsement Wednesday morning at a press conference in North Charleston, Clyburn said he and his late wife, Emily, who died last year, had often talked about Biden.

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“There’s nobody that Emily loved as a leader in this country more than Joe Biden,” the South Carolina Democrat said.

Biden joined Clyburn at the press conference. As he called his friend by his informal first name, Jim, Biden noted that Clyburn is a hero in his community and respected throughout the country.

“Jim has a voice of powerful, powerful moral clarity that is heard loud and clear in the nation’s Capitol,” Biden said.

The No. 3 House Democrat is expected to be the only longtime caucus leader to make an endorsement in the 2020 presidential primary. Speaker Nancy Pelosi and Majority Leader Steny Hoyer have both said they will not express support for any particular candidate but will back the eventual nominee.

“Well, let’s get through the prospects of the election,” Pelosi said Monday in San Francisco when asked whether the current front-runner, Vermont Sen. Bernie Sanders, would hurt Democrats’ chances of holding on to their House majority. “I love the people participating — the people’s choice. We will see how that goes, and we will go from there,” she said.

[Democrats charge ahead after Charleston debate]

Like Clyburn, Pelosi and Hoyer have a history with Biden. They worked closely with the former vice president on many of the accomplishments he touts on the campaign trail, as they led House Democrats during the Obama-Biden administration, the first two years of which they had the majority.

Sanders concerns

Pelosi and Hoyer have also steered clear from backing some of Sanders’ positions, like “Medicare for All” and the Green New Deal, despite support for those ideas growing within their caucus.

The prospect of Sanders — who leads the delegate count after contests in Iowa, New Hampshire and Nevada — winning the Democratic nomination has raised concerns among moderate House Democrats about the down-ballot impact on their races.

Most “Frontline” Democrats — those the party campaign arm considers vulnerable for reelection in 2020 — haven’t endorsed, but those who have are mostly backing Biden or former New York Mayor Mike Bloomberg.

Bloomberg’s campaign commissioned a poll to test the impact a Sanders nomination would have in battleground districts. The survey of 600 registered voters conducted Feb. 22-23 showed Sanders trailing by 1 percentage point in a hypothetical general election matchup against President Donald Trump. But when respondents were reasked the question alongside potential GOP attack lines about Sanders’ self-described democratic socialist positions, Trump’s margin increased to a 6 percentage point lead.

The poll, which has a margin of error of plus or minus 4 percentage points, also found that 39 percent of respondents in the battleground districts would be less likely to vote for a Democratic congressional candidate if Sanders were the nominee and his democratic socialist ideas were in the party platform, compared to 21 percent who said they’d be more likely to vote for a Democrat and 34 percent who said it would have no impact.

Clyburn’s endorsement of Biden likely has little to do with the vulnerable members’ concerns about Sanders, however. He has a longtime friendship with Biden, and several colleagues he’s close with in the Congressional Black Caucus have also endorsed Biden. Former CBC Chairman Cedric L. Richmond, D-La., who has nightly dinners with Clyburn when the House is in session, is a national co-chairman of Biden’s campaign.

In South Carolina, Clyburn’s endorsement is arguably the most influential one Biden could receive. But the former vice president is already ahead in the state. Three polls conducted in South Carolina before the debate showed Biden leading the pack, with Sanders an average of 8 percentage points behind him, according to Real Clear Politics. The most recent of the three, a Public Policy Polling survey conducted Feb. 23-24, had Biden up 15 percentage points over Sanders.

Other candidates who didn’t receive Clyburn’s endorsement can still tout partnerships with him on legislation. Sanders teamed up with Clyburn on legislation to expand funding for community health centers and the National Health Service Corps, and presidential contender Sen. Elizabeth Warren, D-Mass., collaborated with him on legislation to eliminate up to $50,000 in student loan debt for 95 percent of borrowers.

Biden noted the importance of a victory in South Carolina, saying the state frequently backs candidates who have gone on to win the Democratic nomination.

“If you send me out of South Carolina with a victory, there will be no stopping us,” he said. “We will win the nomination, and we will win the presidency.”