Sen. Jeff MerkleyJeff MerkleyOvernight Energy: Fight over miners' benefits risks shutdown | Flint aid crosses finish line in House Senate sends annual defense bill to Obama's desk Dem senator: Trump’s EPA pick is ‘corruption’ MORE (D-Ore.) has raised $1.2 million for his reelection campaign since May 1, bringing his second-quarter fundraising total to $1.8 million. 

It's the best quarter yet for his campaign, and the sum adds to the just over $1 million Merkley posted during the first three months of the year, bringing his total raised for the cycle to just over $2.8 million. His campaign is expected to report $3.5 million in the bank at the end of June with no debt.

Merkley faces a challenge from Republican Monica Wehby in the fall, as the freshman senator tries to hold onto his seat. Merkley has been leading in the polls, but Republicans have hoped to put the seat in play. 

Merkley has spent $1.5 million over the last two months, his campaign reports, in large part due to the aggressive ads he has been running against Wehby, negative spots that seek to link her to the national Republican Party. 

Wehby's campaign has not yet released second-quarter fundraising totals, but the Portland neurosurgeon reported raising just under $600,000 last quarter.