An advertising blitz last month during her uncontested primary campaign has left Democrat Chellie Pingree at a financial disadvantage in her attempt to unseat U.S. Sen. Susan Collins.

Collins, R-Maine, has raised a total of $3.1 million through June 30, a record for a statewide race, according to campaign finance reports filed Monday with the Federal Election Commission.

Pingree has taken in $2.3 million, a record for a challenger.

During the latest five-week reporting period, Collins raised $494,030 and Pingree about $374,000.

But after spending more than $400,000 on television and radio advertising before the June 11 primary, the Pingree campaign has only about $475,000 on hand. By contrast, the incumbent still has $2.3 million.

“We’re thrilled to have such huge momentum and support heading into the fall,” said Amy Abott, Collins’ deputy campaign treasurer.

Pingree decided to advertise early, despite a lack of primary opponent, in order to publicize her message about providing easier access to prescription drugs.

“We knew that it takes television to get the message out,” said Deborah Barron, a Pingree campaign spokeswoman. “We made the decision to do that early.”

Because the Senate is narrowly divided with 50 Democrats, 49 Republicans and one independent, advocacy groups are expected to spend generously in the state as the election grows closer.

One of the Collins campaign contributors is Alan Homer, president of the Pharmaceutical Research and Manufacturers of America, an industry group known as PhRMA. Homer contributed $1,000.

PhRMA’s challenge of a Maine law that allows the state to negotiate with drug companies for lower prices for 325,000 uninsured residents is pending before the U.S. Supreme Court.

Pingree sponsored the Maine law when she was a state senator.