The campaign to keep Washington state's gay marriage law outraised opponents in June.

Washington United for Marriage on Monday announced it raised more than $952,000 last month.

“Our supporters made 4,744 contributions and raised $952,267 for the campaign to defend marriage equality in Washington and approve Referendum 74,” Zach Silk, campaign manager for Washington United for Marriage, said in an e-mail to supporters. “And 79% of our contributions were less than $100.”

“Another very cool stat: 90% of the donations in June came from Washingtonians,” Silk added.

According to Public Disclosure Commission filings that posted Tuesday, Preserve Marriage, the group seeking to overturn the state's gay marriage law, raised just over $17,000 in cash in June, for a total of $139,702.

Washington United for Marriage has raised more than $2 million.

Referendum 74 will ask voters in November to uphold – or reject – a law legalizing gay marriage approved earlier this year by lawmakers. The law is currently on hold pending the outcome of the November vote.

Silk said he expects fundraising efforts by opponents to spike in the fall.

“We can't take anything for granted,” he said.

(Related: Narrow majority of Washington voters support gay marriage.)