Signaling the start of a race that could be just weeks or possibly years away, Democratic Caucus Chairman Bob Menendez (N.J.) has formally launched his campaign for House Majority Whip with a letter to colleagues seeking their support.

The move by Menendez to capture commitments from his Caucus for a post currently controlled by Republicans is an effort to secure his rise in leadership now and discourage any potential challengers, Democratic leadership sources said. It also is designed to temper widespread speculation that Menendez has his sights on the Senate, and the seat of Sen. Jon Corzine (D), who could seek the Garden State governorship next year.

In his letter to Members, dated Wednesday, Menendez laid out why he wants — and believes he deserves — to be the No. 3 Democrat when and if his party reclaims the majority. He said he believes the party is poised to take back the House on Election Day and asked his colleagues to back him when the Whip job opens up.

“I ask for your vote and your support to serve as your Majority Whip, when Leader Pelosi becomes the Speaker, and our current Whip, Steny Hoyer, becomes Majority Leader following a Democratic victory in November,” Menendez wrote to his colleagues.

“It has been an honor to serve as your Caucus chairman, before that as your Caucus vice chairman, and before that as a chief deputy whip,” Menendez added. “I am proud of that successful record of service to the Caucus; and I believe it shows I have the skills, work ethic, and commitment necessary to be a successful majority whip.”

Minority Leader Nancy Pelosi (Calif.) has already said she will run for Speaker and Minority Whip Steny Hoyer (Md.) has said he will seek the job of Majority Leader if given the opportunity. Neither is expected to face any serious opposition.

Menendez, elected Caucus chairman in 2002, said in an interview this week that he kicked off his campaign for the job now because he believes Democrats have a legitimate shot at the majority on Nov. 2.

Menendez can serve another two years as Caucus chairman and said if Democrats remain in the minority in the 109th Congress he would seek that job again — but would also continue his campaign for Majority Whip.

The New Jersey lawmaker said he’s spent the past few weeks trying to shore up his support by personally approaching his colleagues, reaching out to one-time supporters in his Caucus chairman race and calling on lawmakers to talk to their friends about lending him support. He’s also building an outside network of backers, including key Hispanic groups, civil rights organizations and the New Democrat Network.

“I hope to build on this in the next several days,” before Congress recesses, Menendez said.

Rep. José Serrano (N.Y.), a Menendez ally, said he’s helping Menendez in “getting his message out” that the New Jersey Member is running and is deserving of the position. Serrano added that with the election around the corner Menendez is smart to move ahead on his campaign now.

“The timing is perfect, it’s not too early,” Serrano said. “We’re three weeks from finding out whether we have the majority.”

Serrano added that he believes Menendez has widespread support for the Whip job, far beyond what he had just two years ago when he edged Rep. Rosa DeLauro (Conn.) for Caucus chairman. Menendez defeated DeLauro by just one vote in the hard-fought election.

“I believe this time, there are a lot of people who didn’t vote for him last time who now feel he’s done a good job and deserves a promotion, if you will,” Serrano said.

Menendez said his primary goal is winning next month because without a majority, Democrats cannot set the agenda nor can he run for a higher leadership position. He said he has a “laser-like focus” on winning a majority next month.

To back that up, Menendez pointed to his aggressive fundraising and campaigning on behalf of candidates and challengers. He wrote Members that this cycle he has given $550,000 to the Democratic Congressional Campaign Committee, raised another $250,000 for the committee and contributed more than $300,000 to Democratic candidates. He also is touting his efforts to raise more than $2 million this cycle for “Frontline” Democrats, the most threatened incumbents.

Beyond campaigning, Menendez also is telling Members about his work internally, running the Caucus more effectively and with the involvement of more Members, improving Democratic efforts to get on television and radio, and reaching out and solidifying the party’s relationship with the Hispanic community.

“I’m laying out the reasons why I want to be the Whip,” Menendez said. “I think all of that is the foundation — when we achieve the majority that we are all working for — that exhibits to my colleagues that I’ve earned the right to solicit their support,” Menendez said.

“He’s done an outstanding job as the chairman of the Caucus,” said Rep. Jim Davis (Fla.), an early backer. “People appreciate the hard work and focus and the respect with which he treats Members.”

The aggressive push to become Whip comes in the face of long-standing speculation that Menendez wants to be a Senator some day.

Menendez said he “won’t shut the door” on any opportunity, but insisted he has made it clear to House leaders and his colleagues that he is staying put. He noted that he reiterated that commitment even as rumors surfaced this summer that Corzine would resign to take over for resigning Democratic Gov. Jim McGreevey.

“When all that speculation came out, I called Nancy Pelosi, Steny Hoyer and Jim Clyburn [S.C.] and said, ‘Look, I’m focused on and committed to doing what I’ve been doing and that is achieving a Democratic majority in the House,’” he said. “My travel and fundraising hasn’t changed. My focus is on getting a majority and becoming the Majority Whip.”

Menendez as yet faces no challengers, but Democratic sources within the Caucus anticipate it is a possibility. Several Members have ambitions to rise in leadership and could mount a campaign if Democrats win the majority.

While none is specifically rumored to be interested in the Whip job, Members seen as potential leadership hopefuls include: DeLauro, Martin Frost (Texas), Joseph Crowley (N.Y.), Jan Schakowsky (Ill.), Rahm Emanuel (Ill.), Caucus Vice Chairman Clyburn and current senior Chief Deputy Whip John Lewis (Ga.).

“I would hope I wouldn’t have a challenge,” Menendez said. “But I also understand there are no birthrights to any job. I will continue to work for it and earn the support of my colleagues.”