Rep. Nancy Pelosi, the Democratic leader in the House, is celebrating 25 years as a member of Congress on Saturday and the celebrations and commemorations of the milestone have been epic. There have been million-dollar fundraisers and lectures with former presidents; San Francisco streets have been named after her and there were concerts with rock star Bono and the remaining members of the Grateful Dead.

And it is not lost on Pelosi — what a long, strange trip it’s been.

“I’ve exploited it to the hilt,” she joked with reporters recently, adding, “We’ve got music, we’ve got streets, we’ve got bridges. Very immodest.”

The Pelosi celebration tour is the latest evidence that she remains an indomitable force in Democratic politics and unequaled in star power among House Democrats. At the same time the moment has also served to highlight the lack of any obvious heirs apparent to the 72-year-old Pelosi, who is now in her 10th year leading the caucus.

Pelosi, the first female speaker in history, won’t hear any talk of leaving. She remains focused what she calls the “Drive for 25,” the number of seats Democrats need to pick up in November for her to become the first person since the legendary Sam Rayburn, in 1955, to lose the speakership and reclaim it. Part of the reason she chose to publicly exploit this anniversary is the coincidental convergence of the length of her tenure and the number of seats she needs to make history again.

“Did I tell you it’s my 25th anniversary? Did I tell you it’s the same number, ‘Drive for 25,’ for control?” she told reporters Thursday. Taking back the House is an obvious long shot for Democrats, and Pelosi is still recovering from the lingering effects of a $70 million ad campaign by national Republicans in 2010 that demonized her in races across the country, leading to a historic 63-seat loss by Democrats in the midterms. After the drubbing, most members of her own caucus expected Pelosi to resign. She did not, and faced token opposition in her run for minority leader.

Internal rivals acknowledge, even now, that she is secure as head of her caucus and will become speaker if Democrats win the majority this November.

“If she wants to be, if she gets the breaks this fall, she will be speaker,” said Rep. John D. Dingell (D-Mich.), the dean of the House and longest-serving congressman in history.

While she continues to be an unpopular figure among many Americans, Pelosi has receded somewhat from the spotlight that was so inescapable in 2010. This fall the Democrat that Republicans will most seek to undermine is President Obama.

In a special election Tuesday to replace former representative Gabrielle Giffords (D-Ariz.), Republicans have used only a fleeting image of Pelosi and instead focus on linking Democratic candidate Ron Barber to the president.

As if to underscore her reputation for tirelessness, Pelosi left Washington on Friday for a week-long excursion along the Interstate 95 corridor in the Northeast, planning more than a half-dozen stops at fundraisers for the Democratic Congressional Campaign Committee.

Her fundraising efforts are a key reason that in the first four months of 2012, the DCCC has outraised its Republican counterpart, $28.6 million to $26.1 million, an unheard of development for the minority in an election year in which no independent analysts are predicting a Democratic majority. “She hasn’t slowed down 1 mile per hour,” said Rep. Edward J. Markey (D-Mass.), part of a tight clique of veterans that forms Pelosi’s kitchen cabinet.

Some Democrats see the anniversary tour as a legacy-building effort by Pelosi. On Thursday, her colleagues delivered speeches on the House floor honoring her accomplishments, then about 120 Democrats crowded into a first floor committee room for a second surprise party, complete with chocolate cupcakes with “Pelosi 25” written on each. Pelosi’s California colleague, Rep. Zoe Lofgren, also came bearing a gift: a framed copy of Pelosi’s first speech on the House floor, about fighting AIDS.

House Minority Whip Steny H. Hoyer (D-Md.) recalled their days as congressional interns together, back when a male intern had more power and women answered phones. However, according to those present, Hoyer juxtaposed that with the current setting: “Her sitting at the front desk, me in the back — things have never changed.”

Some believe that Pelosi will step down if Democrats do not reclaim the majority in November. If Obama gets reelected, the 2014 midterm elections would provide a historically bad opportunity for congressional Democrats, making the 2016 elections the next chance to claim the majority. If Mitt Romney wins, the 2014 midterms would pose a real chance for Democrats, but Pelosi will turn 75 in March 2015.

No one seems to know what her next move will be. Her friends and her staff profess to have no idea how long she wants to do this job.

“Only she knows that,” said Rep. Anna G. Eshoo (D-Calif.), a close friend.

In some corners Hoyer — her onetime rival for the leader’s post and now her understudy for a decade — is presumed to be next in line. But at 73, even Hoyer’s allies in the caucus call him a “transitional” leader at best.

Waiting on the sidelines are a collection of 40- and 50-somethings: Reps. Debbie Wasserman Schultz (Fla.), currently serving as Democratic National Committee chairman; Chris Van Hollen (Md.), the ranking member of the Budget Committee; Xavier Becerra (Calif.), the No. 5 ranking member of leadership; Steve Israel (N.Y.), chairman of the DCCC; and Joseph Crowley (N.Y.), a top DCCC fundraiser.

Some are viewed as smart legislative tacticians but poor with fundraising skills; others have good political instincts but no legislative heft. Among rank-and-file lawmakers, views of the people in that group indicate that each is slightly better than average.

None is Pelosi, they say.