The departure of Adam Meldrum comes a day after another senior adviser announced he was parting ways with the campaign, saying Cahill couldn't win.
Meldrum, 27, of Michigan, had worked for Strategic National in Michigan, founded by political consultant John Yob, and both worked on US Senator John McCain's 2008 bid for president. Yob brought in Weaver, a fellow McCain consultant. Meldrum had also previously worked for the state Republican party in Michigan.
Cahill chief of staff Amy Birmingham confirmed that Meldrum is leaving, saying in a statement that he "was brought in to this campaign by John Weaver, and he will leave with John Weaver."
Meldrum, whose departure was first reported by the Associated Press, will be replaced by Scott Campbell, who served as campaign manager in Cahill's surprise 2002 victory for treasurer, and who already serves as the top political director and finance director for Cahill's campaign.
Meldrum could not immediately be reached for comment.
Despite the departures, Birmingham said that Cahill would not quit the race and that, "if anything, this has inspired our people even more."
"If the parties had their way, we wouldn't be in this race," she said. "The general sentiment I've experienced on this campaign is that people aren't beholden to parties. Times are changing. People are looking for a new direction."
Cahill, who is in deep third place in the polls, also faces Republican nominee Charles D. Baker, whose campaign relished Weaver's departing comments as a sign of support.
In an interview with the Associated Press, Cahill talked about the exits of Meldrum and Weaver:
Cahill said he was disappointed with both departures, but he said Weaver's involvement had been waning, and Meldrum, while "a great young man," had been largely superseded by Campbell, according to the Associated Press. Meldrum shared McCain roots with Weaver, having worked on the senator's 2008 presidential campaign.
"Scott's been really the presence of this campaign, the leader of this campaign. He's got experience in winning two statewide elections for me," said the two-term state treasurer.
Cahill said he disagreed with Weaver's advice to launch negative attacks against Patrick and Baker, believing it would turn off voters. He vowed to run only positive ads, though he said some will be comparative with the other candidates.
He also lambasted the suggestion by Weaver, as well as members of the Baker campaign team, that his continued candidacy would only serve to elect Patrick.
"That's been a story that the Republicans have been selling and spinning for the last six months," said Cahill. "If their candidate isn't good enough to win this on his own, ... maybe he's not that good."
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