The window for the three combatants for the Republican nomination in the U.S. Senate special election to make a name for themselves is a small one, with the April 30 primary just seven weeks away.

Observers don’t believe there is a clear frontrunner at this point among the field of State Rep. Dan Winslow (R-Norfolk), former U.S. Attorney Michael Sullivan and former Navy SEAL Gabriel Gomez.

But strong fundraising, advertising and ground operations could change that quickly.

Frank Talty, co-director of the UMass-Lowell Center For Public Opinion, believes Sullivan has a “slight advantage” at the moment because of his previous job, but not enough to pull away from Winslow and Gomez at the moment.

“He had received some media attention in that capacity some years ago,” Talty said.

Patrick Griffin, a former GOP consultant and CEO of Manchester, N.H.-based Griffin York & Krause, doesn’t see any kind of frontrunner right now.

Griffin referenced Winslow’s recent victory in a Republican straw poll Danversport Yacht Club in Danvers as not being relevant to the outcome of the race.

“The straw poll doesn’t mean anything,” Griffin said. “Just ask Mitt Romney.”

Talty said Winslow’s win means “he is stronger than some people thought,” but that doesn’t change the race fundamentally at this point.

Winslow, from Norfolk, won 79 ballots in the straw poll, while Gomez, from Cohasset, garnered 59 votes and Sullivan, from Abington, received 55 votes, according to the Boston Globe.

“The biggest problem is no one knows who the hell they are,” said Griffin of the Republicans. “The most interesting thing in this whole race was that (Democratic candidate and U.S. Congressman Edward) Markey wasn’t supposed to be challenged.”

Griffin believes the GOP is going from a “rock star” in former U.S. Sen. Scott Brown to “a third-string opening act” in the current field.

So what do the three candidates need to do in order to become the clear frontrunner?

“If they’re smart, they’ll run a ground game and get as many people out as possible,” Griffin said.

Fundraising is going to prove difficult for any of the GOP candidates given the short timeframe, according to Talty.

“It’s going to be a battle for who can raise the most money,” Talty said, adding that going up with advertising statewide will also help determine who pulls away.

Sullivan and Winslow both have deep connections that could benefit them in the race, according to Talty. Sullivan served in Washington during the Bush years, while Winslow was formerly Romney’s legal counsel and was “very friendly” with former Bush Chief of Staff Andrew Card.

Gomez is attractive as “a young, fresh face” in the state party, and Talty said all three “have a unique appeal.”

It will be an uphill climb for any of the candidates to face Markey (D-Malden) or his challenger, U.S. Congressman Stephen Lynch (D-South Boston) in the special election June 25.

But Talty said there is reason for Republicans to be hopeful. Because there are few other high-profile political races in the country over the next few months, GOP donors will be paying close attention to what happens with this race.

Because of that, if one of Sullivan, Winslow or Gomez separates themselves from the field, they could get the formidable backing of the national GOP establishment.

Then all bets are off for the special election.

“Scott Brown was kind of where these guys are now a few years ago,” Talty said. “He peaked at exactly the right time. Democrats should not take this one for granted.”