Just a week ago, the Democrats’ strategy for winning each of New Mexico’s two Republican-held House seats was remarkably similar.

Each district had an entrenched Republican incumbent, and the leading Democratic challenger was a young, dynamic officeholder that party leaders in New Mexico and Washington, D.C., were very high on — even as they conceded that one race was going to be far tougher for Democrats to win than the other.

But with politics in the Land of Enchantment turned upside-down following Sen. Pete Domenici’s (R) announcement last week that he would not seek re-election, those previously entrenched Republican incumbents aren’t so entrenched anymore.

In the 1st district, Rep. Heather Wilson (R) is off and running for Domenici’s Senate seat, and in the 2nd district, Rep. Steve Pearce (R) seriously is considering joining the race.

National Democratic strategists are increasingly optimistic about their chances of capturing both seats. But the young Democratic officeholders who were trying to unseat Wilson and Pearce — Albuquerque City Councilor Martin Heinrich in the 1st district and Doña Ana County Commissioner Bill McCamley in the 2nd — like it or not, will soon get some company.

“It’s a complete and total free-for-all,” said New Mexico state Rep. Al Park (D), who on Wednesday opted not to run for the 1st district House seat.

With Wilson gone, the Democratic field in her Albuquerque-based district is about to grow.

Former New Mexico Health Secretary Michelle Lujan Grisham is entering the race today. State Treasurer James Lewis also could get in by week’s end. Former state Attorney General Patricia Madrid, the 2006 nominee who finished just 861 votes out of the money, continues to loom large over the race as a potential candidate. And there still are other possible Democratic contenders on the horizon, including Bernalillo County District Attorney Keri Brandenburg.

“I suspect that Martin is probably the most nervous man in politics right now,” said Park, who endorsed Heinrich earlier in the year.

Whether the Democratic roster in the 2nd district changes largely depends on incumbent Pearce’s plans. If he decides to move on, state Sen. Joseph Cervantes (D), who comes from a wealthy, politically powerful farming family, is almost certain to join McCamley in the Democratic Congressional primary.

“If Steve Pearce gets in the Senate race, I can’t think of a bigger battleground state in 2008 than New Mexico,” said Heath Hausseman, a Las Cruces-based political commentator.

Either way, Democrats have become bullish on their chances in the Land of Enchantment.

“I hope the [National Republican Congressional Committee] stocked up on aspirin, because New Mexico just became a huge headache for them,” said Doug Thornell, a spokesman for the Democratic Congressional Campaign Committee.

Fueling Democrats’ optimism isn’t just the prospect of one, if not two, battle-tested House incumbents moving on, but also the knowledge that they would be taking their fundraising prowess to use against each other in a GOP Senate primary, instead of on Democratic challengers.

Wilson in particular is a prodigious money-raiser who banked $754,000 through Sept. 30. Pearce was sitting on $383,000 through June 30.

“That’s a lot of money [Republicans] are going to have to make up for,” said one national Democratic strategist. In the 1st district alone in the previous cycle, the NRCC spent about $2.3 million to help Wilson defeat Madrid.

But Republicans are dismissive of the notion that their New Mexico seats are in jeopardy.

They note that while enrolled Democrats outnumber Republicans in Pearce’s district, southern New Mexico is rural and largely conservative. The district gave President Bush 58 percent of the vote in the 2004 election.

And in the 1st district, national GOP leaders are sky-high on Bernalillo County Sheriff Darren White (R), a former TV news personality who announced his candidacy for the House seat on Wednesday.

“As a crime fighter and a proven vote-getter, Darren White brings a level of experience to the race that is unmatched by any Democrat in the field,” said Ken Spain, an NRCC spokesman.

“He is a formidable candidate with the ability to immediately tilt the race back in the Republicans’ favor.”

Several Democrats concede that White will be formidable.

“He’s a very skilled politician — not to be underestimated,” Park said.

White may not have the Republican field to himself, however. State Rep. Janice Arnold-Jones and state Sens. Joe Carraro and Mark Boitano also are mentioned as possible GOP candidates.

Meanwhile, Heinrich’s media consultant said the candidate feels confident that he will win the Democratic nomination despite the changes in the district’s political dynamic.

“Martin’s been in the race for six months now, and we think that’s a huge advantage for him,” said Maura Dougherty of the D.C.-based firm Envision Communications.

Dougherty could not say what Heinrich’s fundraising numbers for the third quarter would be, but he collected $180,000 in his first few weeks of fundraising before the June 30 reporting deadline.

Back in the 2nd district, Republicans have not yet begun to publicly stir over the possibility of a vacancy and the national GOP hasn’t done any recruiting yet.

Potential Republican candidates there include two businessmen who were runners-up to Pearce in the GOP primary when he was first elected in 2002: Phelps Anderson and Ed Tinsley.