Democrats fret about weak challenge to Brown

The comment overlooked the four Democrats who have already declared their candidacies to take on Brown: Newton Mayor Setti Warren, City Year cofounder Alan Khazei, Democratic activist Bob Massie of Somerville, and Salem immigration attorney Marisa DeFranco.

Warren refused comment, and a Khazei spokesman said in a statement, “He is focused right now on talking to Bay Staters about the issues and their concerns and is not spending time pondering who else may or may not run in 2012.’’

Nonetheless, one Massachusetts Democrat said the Khazei campaign had privately urged the committee Murray leads to stop casting aspersions on the field and instead focus its criticism on Brown. Khazei’s staff is concerned about the effect of Murray’s comments on fund-raising.

Massie said: “It’s disappointing for a group 500 miles away to try to pick a candidate for Massachusetts.’’

DeFranco said national party figures have a “superhero syndrome — they think somebody is going to fly in here with a cape and defeat Scott Brown.’’

She added: “It’s not going to happen that way.’’

Though the current crop of candidates is not nearly as well known, Brown was virtually unknown outside his state Senate district a month before he won the January 2010 special election to replace the late Senator Edward M. Kennedy. Next year, Brown will be seeking his first full six-year term.

Patrick declared Thursday that the incumbent senator is “eminently beatable,’’ labeled the group of prospective Democratic challengers “great,’’ and repeated that he has no intention of being the big-foot candidate the national Democrats continue to seek.

The governor has also promised to not endorse any candidate early, saying a contested primary — like the one he faced in 2006 — will boost the party by elevating the statewide profiles of the candidates and producing a trail-tested winner who can take on Brown.’’