As John Kerry was gaining strength earlier this month in the critical swing state of New Mexico, national Republicans began to fret that a Democratic surge in the Land of Enchantment could swamp perpetually vulnerable Rep. Heather Wilson (R-N.M.).

But Wilson’s Democratic challenger, state Senate President Pro Tem Richard Romero, may have halted his own momentum by recently airing an attack ad that suggests Wilson’s votes in Congress gave aid and comfort to Osama bin Laden.

Running a picture of bin Laden’s face next to Wilson’s, Romero charged that the incumbent voted against a measure that would have increased inspections of airline cargo.

Republicans believe the TV ad may sink Romero, a shoot-from-the-lip politician who trailed Wilson by just 1 point in an independent poll taken in early October. That’s progress from a month earlier, when Romero trailed by 7 points, and from their first matchup in 2002, when Wilson took 55 percent of the vote.

“I don’t know what possessed him to do that,” Mickey Barnett, a former Republican National Committeeman from New Mexico, said of the ad. “Personally, I think the race ended right there.”

“It was a very close race,” said Chris Paulitz, a spokesman for the National Republican Congressional Committee. “But I have a tendency to think he lost all independents and a lot of Democrats.”

The disposition of independents and Democrats is key in the Albuquerque-based 1st district. Although 47 percent of the district’s voters are Democrats and 16 percent are independents, Republicans have confounded Democrats by holding the seat since 1968.

Wilson has been on the Democrats’ hit list ever since she narrowly won a special election in early 1998, and her showing in 2002 was far and away her strongest. But Democrats believe that Romero is a savvier, more battle-tested challenger this time. And with Gov. Bill Richardson (D) ginning up the Democratic vote statewide, Congressional Democrats have assumed that Romero will benefit.

“We’re locked and loaded,” said Greg Speed, a spokesman for the Democratic Congressional Campaign Committee. “It’s still one of our best [pickup] opportunities.”

No polling has been released in the race since the bin Laden ad aired, and Democrats see the fallout far less apocalyptically. They believe Romero is scoring points by hitting Wilson hard, and argue that the substance and topic of the ad — the safety of America’s air traffic — is resonating among security-conscious voters.

“Republicans are trying not to talk about the real issue,” said Kena Hudson, a spokeswoman for Romero. “It’s a serious issue and it’s something the people in the district are concerned about.”

But while Romero has aggressively tried to tie Wilson to President Bush — and her slippage in the early October poll seemed to be directly related to Bush’s own slide — it was Wilson who proved the aggressor Sunday in their only televised debate.

Romero did talk about “the two Heathers” — one who casts herself as an independent back home while she’s voting in lockstep with the conservative Republican majority. But according to published analyses of the debate, Wilson was relentless, hitting Romero on multiple issues, including missing votes in the state Legislature.

“He didn’t show up for work,” she said.

Seeking to bolster her reputation as an independent, Wilson said she has been approached by Democrats about switching parties — though she offered no details, and Romero did not follow up.

And responding to a question from Romero about whether she would pledge to never vote to privatize Social Security — something Romero’s ads have been accusing Wilson of favoring — the Congresswoman caught her challenger by surprise by answering succinctly: “Yes.”

Romero was left to reply, “I’m glad to see she’s coming along, finally.”

It was a vintage performance for the steely Wilson, an admired if not particularly beloved figure in New Mexico who is the first female veteran to serve in Congress.

“Heather is very disciplined,” Barnett said. “That’s her background. That’s her persona.”

Brian Sanderoff, an Albuquerque-based pollster who has been measuring the race for the Albuquerque Journal, said the Wilson-Romero contest has been far and away the nastiest in the state other than the presidential election itself. But he said it is difficult to measure whether the angry exchanges benefit one candidate or the other.

“From the ads, you’d think they’re both unpatriotic and criminal,” Sanderoff said. “When you get to the point where they are, the voters become cynical.”

Both Wilson and Romero have been spending liberally to get their message out. Wilson spent $1.68 million from July 1 to Sept. 30 alone and had $412,000 in the bank. Romero spent $954,000 in the same three-month period and had $262,000 left to spend.

Both parties’ Congressional campaign committees are also on the air in the 1st district and expect to be through Election Day.

Still, while Republicans are publicly expressing satisfaction with Wilson’s standing in New Mexico — and Bush’s — they are sufficiently concerned that they are already raising the specter of possible voter fraud between now and Nov. 2.

With absentee and early voting already under way in the Land of Enchantment, there has been controversy about the types of identification voters will have to show at the polls, and charges and counter-charges about the propriety of certain voter registration drives.

In Albuquerque, for example, a worker for the liberal group ACORN wound up registering a 13-year-old boy. And the Republican-appointed U.S. attorney for New Mexico has already served notice that he plans to watch the balloting closely.

“These liberal 527s have helped Romero,” Greg Graves, the executive director of the New Mexico Republican Party, acknowledged. “They’re illegally registering voters and have created an atmosphere that might help him close the gap” with Wilson.

CLARIFICATION:

The Oct. 19 article “The ‘Unpatriotic’ vs. the ‘Criminal’?” incorrectly reported that Rep. Heather Wilson’s (R-N.M.) Democratic challenger ran a TV ad featuring Wilson’s image side-by-side with that of Osama bin Laden. The ad did feature a picture of bin Laden and the accusation that some of Wilson’s votes in Congress aided terrorists.