National Democrats have done their best to clear the field for Rep. Edward J. Markey in the expected Massachusetts Senate special election, but as the 113th Congress opens Thursday, there are other Democrats still eyeing the race.

Bay State insiders believe that Markey could have a straight shot at the Democratic nomination, pending Sen. John Kerry’s expected confirmation as secretary of State. But that hasn’t happened yet.

Rep. Michael E. Capuano and state Sen. Benjamin Downing are still pondering a run for Senate, aides to each said on Wednesday. Rep. Stephen F. Lynch has expressed an interest in higher office as well, but his office didn’t answer queries as to whether he was pondering a run.

Markey, the 66-year-old dean of the Bay State’s congressional delegation, has the endorsements of Kerry, the Democratic Senatorial Campaign Committee, and Vicki Kennedy, the wife of late Sen. Edward M. Kennedy. A June special election, at the earliest, is expected.

Whether Markey faces a bruising primary battle or can focus all his resources on the general election — he had a respectable $3.1 million in his federal account on Nov. 26 — could well determine whether he becomes a senator or remains a congressman.

Former Rep. Marty Meehan, D-Mass., currently the chancellor of UMass Lowell, told CQ Roll Call that Markey is “positioned extremely well.” But, the former congressman warned, “I think everybody in Massachusetts recognizes that a tough Democratic primary battle means Scott Brown’s election.”

Brown, the outgoing Republican senator from the Bay State, appears to not have made a decision yet on a bid to return to the chamber.

“Scott is still thinking,” a Massachusetts Republican operative said. “You know what an insane commitment these thing are, no one jumps into them lightly.”

The source said the senator was huddling with his family and advisers. A decision is expected in the next two weeks.

Colin Reed, a spokesman for Brown, declined to comment.

But in a radio interview Wednesday morning, Brown jokingly knocked Markey.

“I’ll tell you what; They’re making it awfully tempting. You got Ed Markey: Does he even live here any more?” Brown said, according to a Boston Globe write-up of the interview.

That appears to be an early line of attack on Markey from the GOP: that he’s gone Washington, both in where he lives and how he acts.

“He’s pretty much the quintessential D.C. insider,” veteran Massachusetts GOP strategist Rob Gray said, noting he thought Brown had a good shot against Markey in a special election.

Of course, Markey’s campaign pushed back strongly against the assertion that he wasn’t still a Massachusetts man.

Giselle Barry, a Markey spokeswoman, said in a statement Brown was “launching false, personal attacks from the sidelines.”

“Ed Markey lives in Malden, and has lived there his entire life. He and his wife own their home in Malden. He is proud to come from and represent the values of the people of Malden,” she said.

Malden is a middle-class town of about 60,000 people just north of Boston. Markey also has a home in Chevy Chase, Md.

If Markey’s long tenure in Congress can be framed as a weakness by Republicans, his legislative accomplishments can also be framed as a strength by Democrats.

Meehan said that Bay Staters want a senator who could move big legislation in the Senate, not just for them, but for the country, too.

“Voters are going to be looking for someone who can not just be good for Massachusetts, but can also have a national impact,” he said. “Ed Markey has that track record.”

Markey’s legislative accomplishments include the vast 1996 telecommunications law.

For his part, Meehan, who had $4.7 million in his dormant federal account at the end of September, said he wasn’t going to run for the Senate seat.

But some of his former colleagues haven’t made that decision — yet, anyway.

Last month, Capuano bristled at the DSCC’s endorsement, saying in a statement that “the big names of our party are trying to choose our nominee for us.” Noting he had won previous elections running against the establishment, Capuano said, “If I make this run, it will be the same way — from the streets up, not from the elite down.”

Ironically, it was Markey who ran against the establishment in a crowded 1976 open-seat primary when he first won his seat in Congress. He began his primary campaign as an ambitious 29-year-old state representative who had tangled with the Democratic establishment. He ended it by beating 11 opponents to get the Democratic nod.

Downing, the state senator eyeing a bid, got married on Sunday and met with advisers on Wednesday. The expectation is if he moves ahead with a run, he will do so in the next two weeks. One adviser hinted if he did run, he would run a “positive, grass-roots campaign.”

Once Kerry is confirmed, Democratic Gov. Deval Patrick is likely to appoint a placeholder senator who will pledge not to run in the special election, and the clock will start on the Senate special.

But until then, insiders said, each day that goes by without a challenger from his own party gives Markey a better shot to take on whomever his Republican challenger will be.