There are two long-time U.S. representatives running on the Democratic side: Ed Markey of Malden and Stephen Lynch of South Boston.
As for Winslow, 54, there's no doubt this would be a tough battle because of his low name recognition, but that might be a good reason to do it. After all, Brown was relatively unknown when he was elected.
Another GOPer still being discussed is former Navy SEAL Gabriel Gomez, who is meeting with national Republicans this week.
Boston GOP consultant Rob Gray said "waiting as long as he did, Scott Brown put the party in a tough spot."
"The February 27th signature deadline is more of a roadblock than a speed bump. Ten-thousand signatures is not easy to achieve in a three-week period when you are starting from scratch," Gray said, adding that's why, despite the "exploratory committee," he's not completely convinced Winslow will get in with Gomez already meeting with national Republicans.
"If there's one candidate the party gets behind, even with the limited infrastructure of the party plus the candidates and the candidate's campaign and resources, they could meet the signature deadline. If it's two guys competing to get 10,000 signatures without the assistance of the party and their resources it's highly unlikely one or both don't make it," Gray said, noting the party is required to stay neutral among all Republican candidates who get in.
Signatures for a Republican candidate can only come from registered Republicans or registered Independents.
"When you think about registered voters, plus no Democrats, more than half of the people you approach at a shopping mall can't legally sign your signature sheet," Gray, a consultant at Gray Media, said. "It's not impossible, but there are not a lot of Republicans in this state. There are not a lot of arms and legs and field troops. When you split already limited resources between two candidates, it's certainly not impossible, but getting the signatures will be difficult."
Does the possibility of not having a high-profile name or even a credible candidate in 2013 do anything to hurt the probability of Republicans' taking the seat in 2014? Gray thinks they are "unrelated."
"A lot of potential candidates who were put off by the late negative decision by Brown for the special election would consider the 2014 race. assuming that a Democrat wins the special election," Gray said. "Similar to Brown, some of the names floated about these past few weeks looked at it and said, 'Why do I want to run in a special to wake up the next morning and start to run again in 2014?' I don't think it does impact the 2014 race."
Gray noted that a gubernatorial election year could also be better for Republicans, but added he does believe Brown would have ended back in the Senate if he had gotten in.
"I think if Brown would have gotten in, he would have won," Gray said, "but I guess he didn't think that."