Rep. Richard Gephardt (D-Mo.) will unveil a list of roughly four-dozen previously uncommitted House supporters of his presidential bid within the next three weeks, capping the announcement with the endorsement of Minority Leader Nancy Pelosi (D-Calif.).

Several well-placed Democratic sources said Gephardt will roll out his House backers before the Memorial Day recess, which begins May 24. Sources said Gephardt, who served as the Minority Leader for eight years, will headline the event with current House leaders Pelosi and Minority Whip Steny Hoyer (D-Md.).

“I’d be surprised if this doesn’t happen before Memorial Day,” said one Democratic staffer whose boss is supporting Gephardt.

Gephardt has been courting his House colleagues — and Pelosi in particular — for months. Just before the April recess, Gephardt renewed his plea for Pelosi’s endorsement.

Sources said Pelosi has been leaning toward backing Gephardt for some time, but was being deliberate in her approach. Gephardt, on the other hand, has been flexible regarding her timetable because of his strong desire to have her atop the list, sources said.

It is unclear precisely how many Members will sign on with the Gephardt presidential campaign at the event, but several Democratic sources said the number should hover around 50.

The Gephardt campaign won’t reveal any details about the upcoming announcement. One adviser insisted the timing is still uncertain: “We’ll see. No decisions have been made.”

Asked whether Pelosi was ready to come on board, the same adviser said: “We’d like to have her endorse us, we’d like to have Hoyer endorse us, we’d like to have lots of people endorse us.”

Rep. Robert Matsui (D-Calif.), publicly supportive of Gephardt for some months, said there will be a “substantial number of Members.” However, the chairman of the Democratic Congressional Campaign Committee said the Gephardt camp feels no pressure to speed up the release of its list just because other presidential hopefuls including Sen. Joe Lieberman (D-Conn.) have done so.

“My guess is he’s waiting for a few other people that are inclined to endorse him,” Matsui said.

Matsui wouldn’t reveal names, but added that Gephardt is trying to land Members who will help him “make a significant splash” when he does roll out his backers.

“It could be worth his wait,” he said.

“You will be impressed with the quality and quantity of Members that we roll out,” said Rep. William Lacy Clay (D-Mo.), Gephardt’s national co-chairman.

While Gephardt allies say he is comfortable taking his time, other prominent Democrats confirmed the former Minority Leader is starting to feel the heat to advance his announcement sooner rather than later.

“I think there’s pressure for Gephardt to deliver support in a timely fashion given what happened before with Lieberman,” when the Connecticut Senator laid out his House backers, said the Democratic aide. Lieberman is backed by 11 House Members, and in recent days Rep. Harold Ford Jr. (D-Tenn.) announced his support for Sen. John Kerry’s (Mass.) presidential effort.

While Gephardt has yet to unveil a list, many House Democrats already have publicly endorsed him. Among them are: Matsui, Clay, Budget ranking member John Spratt (S.C.), Rep. John Murtha (Md.), Rep. Sherrod Brown (Ohio) and Rep. Patrick Kennedy (R.I.).

Pelosi would be key for Gephardt, given her prominence in the Caucus, fundraising capabilities and ties to women and the liberal base. Several sources said Pelosi had been waiting to give Gephardt her endorsement until it was clear Sen. Chris Dodd (Conn.) was out of the running.

Pelosi attended college with Dodd’s sister, and the two are longtime friends.

Gephardt and Pelosi also wanted to wait until after the war in Iraq had concluded. Pelosi and Gephardt clashed on the issue and didn’t want the announcement to focus on their differences.

“I don’t think it was ever much of a decision for Pelosi,” said the aide. “She’s taking it cautiously. She’s the Democratic leader. She’s being methodical and careful in her approach to what she’s going to do.”

Pelosi’s office won’t talk about any endorsements. Spokesman Brendan Daly offered a solid “no comment” when asked about whether his boss will be among Gephardt’s House supporters.

Matsui noted that unlike in 1988 when Gephardt sought the presidency, the Missouri lawmaker already has legitimacy. He doesn’t need the names of House backers like he did 15 years ago.

“He doesn’t really need the Caucus like he did in ’88,” Matsui said. “He’s a known quantity.”