With Rep. Tom Udall (D-N.M.) now officially vacating his 3rd district seat to run for Senate, myriad Democrats in heavily Hispanic northern New Mexico are mobilizing to replace him.

The field of potential candidates is as deep as it is intriguing. It comprises Hispanics and Anglos; rival Hispanic families; statewide elected officials; local power brokers; members of the established, old guard of moderate Democrats; and a new generation of up-and-coming liberals.

Just who emerges with the upper hand in the early June primary campaign remains to be seen: Democrats are declining to play favorites at this point — at least on the record.

“New Mexico Democrats in our 3rd Congressional district are fortunate to have a large, well-qualified, diverse and accomplished field of candidates from which to choose to send to Congress,” state Democratic Party spokesman Jonathan Neal said Monday.

Ultimately, the primary field might be capped at five candidates. A bill signed into law by Gov. Bill Richardson (D) earlier this year requires any candidate who makes the ballot to earn at least 20 percent of the vote among party delegates at a preprimary nominating convention. The state Democratic Party’s nominating convention is scheduled for March 15.

State officials are attempting to amend a glitch in the law — which eliminated a candidate’s option to petition onto the ballot — as the Democrats could conceivably end up with no 3rd district nominee at all if a severely crowded convention creates a situation in which no candidate wins at least 20 percent of delegate votes.

At least in the short term, the Democrats viewed as potential frontrunners in the 3rd district primary include Don Wiviott, a wealthy developer who dropped out of the Senate race over the weekend immediately following Udall’s announcement that he was getting in.

Also on the list of possible Democratic frontrunners are former Santa Fe County Commissioner Javier Gonzales; Geno Zamora, former legal counsel to the Richardson administration; state Auditor Hector Balderas; Española Mayor Joseph Maestas; and Ben Ray Lujan, the elected chairman of the state Public Regulation Commission and son of New Mexico Speaker Ben Lujan (D).

One Democratic strategist familiar with the district, which includes the state capital of Santa Fe, predicted that Hispanics would push to elect a nominee who shares their ethnicity.

Some Hispanics in New Mexico are frustrated that the state’s Congressional delegation has been all-white for the past decade, even though whites and Hispanics are roughly equal in population.

However, it’s far from guaranteed that the winner of the 3rd district Democratic primary will be Hispanic.

“The fact that Udall has held that seat for so long and is pretty popular shows that [ethnicity] is not a deal breaker,” the Democratic strategist said. “Hispanics could end up splitting the vote in the primary and that would leave room for someone like Don Wiviott to come in.”

Udall, a former two-term state attorney general, was first elected to the House in 1998. His cousin, Rep. Mark Udall (D), is running for Senate in Colorado.

Although some potential candidates in the 3rd district Democratic primary are seen as immediate frontrunners should they run, several others also could threaten for the nomination should they enter the race.

Among them are Santa Fe County Sheriff Greg Solano. He already has made preparations to run for lieutenant governor in 2010, but has solid name identification and has indicated he would consider running for Congress.

State Rep. Peter Wirth (D) also might run. Wirth had announced for state Senate in part because Udall had originally vowed to run for re-election to his House seat. But some believe Wirth, who is the nephew of former Sen. Tim Wirth (D-Colo.), could change his mind.

Former state Rep. Patsy Trujillo is the only woman who is openly considering the race, a factor that could prove advantageous, particularly if EMILY’s List decides to endorse her. Trujillo has also worked for the governor and was an aide to Richardson when he served in Congress.

The Democratic Congressional Campaign Committee is confident that its eventual nominee in the 3rd district will be spared a major challenge in the general election, noting that House Republicans are focused on retaining New Mexico’s 1st and 2nd districts. Reps. Heather Wilson and Steve Pearce have vacated those seats, respectively, and are running against each other in the GOP Senate primary.

The 3rd district would be a stretch for Republicans anyway, as the Democratic presidential nominee won the district with 54 percent of the vote in 2004 even as President Bush won statewide with 50 percent.

“This is solid blue territory and Democrats will have a strong candidate,” said DCCC spokesman Doug Thornell. “Mounting a challenge in New Mexico 3 seems unlikely for a party on the defense.”

With so many prominent and connected Democrats pondering a 3rd district run in 2008, New Mexico’s tangled web of party politics could be tested over the next 12 months. Wiviott appears to be the only real outsider in this race, although his stated willingness to spend plenty of his own money could give him an immediate advantage.

The rest of the field brings a host of political, familial and political ties to the table.

In the case of Lujan, the PRC chairman, there is speculation that his father, the New Mexico Speaker, might attempt to clear the primary field for him. The elder Lujan is an ally of Richardson’s and has long been a major political power broker in northern New Mexico.

But earlier this year, he only narrowly survived an intraparty coup to oust him as Speaker, so it is possible that his power has been diminished.

Gonzales, the former Santa Fe County commissioner, comes from a prominent northern New Mexico family that owns a popular bilingual radio station (his father was a former Santa Fe mayor). Wirth’s grandfather was one of the main architects behind the development of Santa Fe. But as a member of the state House, Wirth’s life could be made difficult by Speaker Lujan if he decides to oppose Lujan’s son, and that might discourage him from abandoning his state Senate campaign to run for Congress.

Maestas, whose wife is a federal judge, is mayor of a key population center in the 3rd district, and is based in Rio Arriba County, a major Democratic Party power center. He served as a city councilor before becoming mayor, but could encounter resistance from the Naranjo political machine, named for former state Sen. Emilio Naranjo, the county Democratic boss for 50 years.

Naranjo is representative of the typical old-school New Mexico Democrat, and for years any candidate to emerge from Rio Arriba County and perform well at the ballot box in that region of the state had to pass muster with him. But Maestas is part of a new generation of liberal Democrats who have begun to experience political success in the north.

Balderas, the state auditor, has good name identification and is pretty popular statewide, including in the 3rd district, where he was formerly a member of the state House. He is considering running, although he was elected to his current position just last year.

Zamora, who now is practicing law, comes from a well-known northern New Mexico family. He ran for state attorney general last cycle and lost in the Democratic primary to Gary King in part because he split the Hispanic vote with Lemuel Martinez. King, who went on to win the general election, is the son of former three-term Gov. Bruce King (D).

Zamora accrued some favorable name recognition during that race and could be a formidable candidate in the 3rd district.

New Mexico Democrats are attempting to sort out the field and figure out who would be the best candidate to replace Udall. With the state’s two other House seats open and the Senate seat also open, both Democrats and Republicans have been scrambling to get a handle on their respective 2008 primary contests.

“The upheaval we’ve experienced is confusing,” one New Mexico Democratic insider said. “We’re still trying to figure out who the strongest candidate is going to be.”