With the clock ticking for Democrats to find a viable challenger to Rep. Marilyn Musgrave (R-Colo.) — whose vocal opposition to gay marriage has made her one of the biggest lightning rods for controversy in Congress — their hopes appear to rest on two vastly different state legislators.

One is a former self-described “athletic missionary” and college professor, and the other is a colorful rancher whose plans could include campaigning across the sprawling 4th district with a mule named Marvin.

“Clearly it’s a targeted seat,” said Democratic Congressional Campaign Committee spokeswoman Sarah Feinberg, who added that the demographics in the heavily Republican district were shifting in the Democrats’ favor. “We think she’s very vulnerable.”

But even though the two-term Representative won re-election with just 51 percent of the vote in November and is listed on the Republican leadership’s most vulnerable incumbents list, there is plenty of doubt that the Democrats can make a real run at Musgrave.

“Once you become vulnerable you stay vulnerable unless you win really big,” said Floyd Ciruli, an independent pollster in Denver. “This will be her test election.”

But Ciruli added: “It will take a tremendous confluence of good fortune for the Democrats” to win.

Leading the list of potential contenders is state Rep. Angie Paccione (D), a born-again Christian and former USA women’s basketball team member, who has served as an athletic missionary throughout Europe. Paccione, who describes herself as biracial, launched an exploratory committee earlier this month and is polling in the district because the “people of the 4th have asked me to take a look at running.”

Paccione, who said she first wants to see how well her profile resonates in the district before throwing her hat in the ring, plans to make a decision on the race by the end of July. At the moment, Paccione, who is a research associate at Colorado State University, is widely viewed as having an advantage when it comes to organization and personal drive.

“Maybe a better candidate will come along but I haven’t seen it,” said Colorado Democratic Party Chairwoman Pat Waak.

Another potential contender is state Rep. Wes McKinley, a self-described “Bible-thumpin’, whiskey-drinkin’, gun-totin’ Democrat.”

In news accounts, McKinley suggested that he may defer to Paccione should she prove the stronger candidate against Musgrave. But the cattle rancher sounded a slightly more combative note in a recent interview.

“Angie can’t even ride a mule,” he said. “She’s terrific, but in order to win she’d have to dribble a basketball all across this district.”

McKinley said his beast of burden was one of several factors he had working in his favor, in addition to his “loyal dog” and “a hardworking wife.” The 14-year-old mule, who goes by Marvin, may play a role on campaign stops across the district, McKinley said.

But despite his optimism, McKinley didn’t sound as if he was in much of a hurry to make a decision on the race, noting that his priorities this summer were “fixing fence and getting the cows branded and castrated.”

Both candidates have potential weaknesses.

While McKinley’s politics may be closer ideologically to the district’s, Ciruli said, “the first impression he leaves is that he is just really colorful. … Maybe just a little bit too eccentric.”

Meanwhile, Paccione, who lives in Fort Collins, could be vulnerable to charges that she represents liberal, “college professor politics,” Ciruli said.

A third potential contender, former state Sen. Peggy Reeves (D), has been touted by some Colorado Democrats as the strongest candidate, though she is not considered likely to make the race.

Instead, Reeves said she was working with a recently formed group called the 4th Congressional District Committee to lay the groundwork for “whoever is the candidate.”

“I want to make sure we have a viable candidate running against Marilyn,” she said. “That’s why I’m not ready to say I’m absolutely not running.”

The degree of Musgrave’s vulnerability — in a district that went for President Bush by 17 points last year — remains a matter of debate.

In addition to being on House Majority Leader Tom DeLay’s (Texas) ROMP list of 10 endangered GOP lawmakers, Musgrave may have primary opposition. Former state Rep. Bill Kaufman, a Loveland attorney and moderate Republican, has said he is considering a challenge to the conservative Musgrave.

And while the liberal group MoveOn.org recently took to the airwaves, running radio ads attacking Musgrave’s support for the embattled DeLay, some state Democrats are already expressing doubt about the wisdom of mounting a major challenge against her.

“I think they’ve written off the seat,” said one Colorado Democratic source of the party’s major funders. “I do think people get tired of pouring money down a drain.”

Even Waak, who believes many Rocky Mountain Republicans are disenchanted with the “radical right,” conceded that Musgrave’s eventual challenger could face an uphill road.

In addition to a roughly 60,000-voter registration disadvantage, the Democrat could have to contend with a rumored effort to get a proposed constitutional amendment banning gay marriage on the state ballot in 2006, which, if it proves successful, would “drive a lot of people who share her ideas” to the polls, Waak said.

National Republican Congressional Committee officials don’t appear to be anticipating much of a fight.

“We do not expect to” pour that many resources into the race, said NRCC spokesman Carl Forti. “Not at this point in time. We don’t know that she’ll need it.”

Musgrave Chief of Staff Guy Short was similarly sanguine. He attributed Musgrave’s lackluster performance last cycle to the “over $2 million spent by 527s and their supporters” and ads against her “that Time magazine called the sleaziest ads in America.”

What’s more, Short said, Musgrave anticipated reporting “over $500,000 on hand” at the end of the second quarter, including the more than $200,000 she brought in from a Denver fundraiser last month with Vice President Cheney.

Some Democrats have accused Musgrave, who as a freshman gained notoriety as the chief House backer of a constitutional amendment to ban gay marriage, of devoting too much attention during her Congressional tenure to hot-button social topics at the expense of bread-and-butter district issues.

Musgrave’s “not focusing on the kitchen-table issues,” Paccione said.

Those arguments may have contributed to Musgrave’s surprisingly weak showing last year in her rematch against state Sen. Stan Matsunaka (D).

But another Democratic Colorado source said that Musgrave “unfortunately, I think … was scared by that experience. She’s been working the district more aggressively and raising money and she hasn’t been taking the seat for granted.”

And when it comes to sensitive social issues, neither of the two most likely Democratic contenders appears eager to take any definitive positions. (Short says polling in the district done for Musgrave shows “over 70 percent support” for traditional marriage, defined as between a man and a woman.)

Paccione, who is opposed to a constitutional amendment banning gay marriage, nevertheless also said she was “not for redefining marriage” and supported the Defense of Marriage Act. Just to make sure there was no confusion, she later sent an e-mail asking that she not be lumped “in some predetermined category.”

“I am not opposed to a state’s right to approve of same-sex marriages or civil unions or domestic partnerships,” she wrote. “I am anti-discrimination and pro-social justice.”

Meanwhile, McKinley also refused to directly answer the question of whether he supported gay marriage, though he did say he would support legislation to legalize it if its basis was to protect “liberties and properties.” He also said that he was opposed to abortion, but had “checked with Christian doctors” who had told him “you can’t make it illegal ’cause it would be worse.”

Eventually, other contenders could come forward in the coming months. One of the Colorado Democratic sources said there were still “voices in the party” who felt that more recruiting needed to take place.

“I don’t think the Democrats have come to a firm conclusion about who they need to support,” the source said.