Charlie Baker surges financially.

In one of the most aggressive political fund-raising pushes in recent memory, Republican gubernatorial hopeful Charles D. Baker has amassed a $1.85 million war chest over roughly five months of campaigning, tapping into a broad range of supporters and establishing himself as a major threat to Governor Deval Patrick’s reelection bid.

Baker doubled, in less than half the time, what Patrick raised for the entirety of 2009, despite a fund-raising visit by President Obama this past fall for the Democratic governor. Baker’s coffers currently hold more than 10 times the amount in Patrick’s campaign account.

The Republican has also raised 3 1/2 times the amount that state Treasurer Timothy P. Cahill, an independent rival in the governor’s race, collected last year. Baker’s rival for the Republican nomination, Christy Mihos, lags far behind, relying mostly on personal wealth.

Baker’s fund-raising haul, which has broken records for a nonincumbent candidate who is not yet a party nominee, provides another jolt for Democrats already discouraged over Patrick’s underwhelming poll numbers and comparatively slow pace of fund-raising.

“This is the political fund-raising version of shock and awe,’’ said Warren Tolman, a Democrat and former state senator who ran for governor in 2002. “Baker has cast a pretty wide net.’’

Campaign finance records show that Baker has collected $2.3 million since late summer, when he assembled a team of Republican fund-raisers and set up events almost nightly from Labor Day into late December. In addition, his running mate, Richard Tisei, the Senate minority leader, who joined the ticket in late November, raised $313,000.

Last month, typically the toughest of the year to collect political donations, Baker reported raising a whopping $726,000, ending the year with a donor base of 7,449 people. Raising money every year is key for candidates in Massachusetts, because the annual contribution limit for individuals is $500.

The fund-raising success has allowed the campaign to spend hundreds of thousands of dollars already to position itself for this election year.

Baker’s feat exceeds the expectations his aides had when the former CEO of Harvard Pilgrim Health Care decided to jump into the 2010 governor’s race.

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