Coakley rejects claim she was reluctant to investigate DiMasi

Attorney General Martha Coakley on Monday rejected claims by a former inspector general, Gregory Sullivan, that her office was reluctant to pursue an investigation against Salvatore F. DiMasi, the corrupt former House speaker, in 2008.

“I don’t know why Greg Sullivan is saying that, but he is absolutely wrong,” said Coakley, the Democratic candidate for governor, at a campaign stop at a construction site.

Coakley, who ceded the prosecution of DiMasi to the US attorney’s office, said her office “worked cooperatively with the federal government on the case against the former speaker.”

Speaking to reporters during a campaign stop in Worcester, Coakley’s Republican opponent, Charlie Baker, called Sullivan “very credible’’ and called the allegation made by Sullivan “disturbing.’’

“Greg Sullivan is a very credible person and a longtime public servant — a Democrat who, I think, was a surrogate for the Obama administration in both of President Obama’s campaigns, who did a lot of very important work when he was inspector general,’’ Baker said.

Baker added, “I think the issues he raises are serious and disturbing, and I think the attorney general owes the voters an answer on it.”

Sullivan, who investigated DiMasi in 2008, told the Globe in a story published Sunday that Coakley had told him at the time to stop his inquiry. “My takeaway,” Sullivan told the Globe, “was that they were not anxious to go prosecuting the speaker of the House.”

Coakley on Monday strongly disputed Sullivan’s version of events. “That conversation didn’t occur the way he said it did,” she said. “I don’t know why he’s saying it, but he’s just wrong. All of the documentation and the results show that we cooperated with that investigation.”

In taking questions from reporters, the attorney general also shrugged off the suggestion that Baker appears to have momentum in the race.

“We have a great grassroots team,” she said. “We have called and e-mailed and talked to so many people around the state. I am totally convinced that we have the momentum here.”