Mayor Ron Nirenberg continued to raise and spend more money than Greg Brockhouse in San Antonio's mayoral runoff, according to new campaign finance reports released Friday, but the challenger brought in his largest haul of the year.

Nirenberg raised $329,770 and spent $321,755 between April 25 and May 29, according to his form. He reported having $95,588 left on hand going into the campaign’s final week.

Brockhouse raised $114,675 and spent $105,135 in that same span, with $28,531 left over as of May 29.

While he still trailed Nirenberg’s campaign by a margin of 3-to-1, Brockhouse’s report represented an improvement from his fundraising numbers before the May 4 general election, when he was raising significantly less money than any serious mayoral contender of late.

He raised more money over the last month than he had in the four previous ones combined.

On ExpressNews.com: San Antonio mayor’s fundraising far outstrips his challenger, but unions could help narrow the gap

The police and fire unions, which are supporting Brockhouse, helped him narrow that financial divide during the general elections. It’s not known yet how much they have spent on the runoff because they aren’t required to file another disclosure until Wednesday.

Other outside groups, including the Texas Organizing Project, will also report Wednesday. TOP endorsed Nirenberg in the runoff.

Separately on Friday, the San Antonio Chamber of Commerce called out the police union for what the chamber claimed was a misleading advertisement against Nirenberg.

The mailer shows a check made out to the mayor for $3 million from “City Hall Insiders.”

“Why have special interest groups, lobbyists, PACs, and Fat Cats given Ron Nirenberg $3 million in campaign cash?” the advertisement reads.

But the list of donations was made up of contributions to the Go Vote No campaign, not Nirenberg’s re-election bid.

Go Vote No was an effort Nirenberg led last year to defeat a set of charter amendments pushed by the fire union that most city leaders warned would be harmful.

On ExpressNews.com: Police, fire unions have spent $268K during San Antonio’s election cycle this year

Chamber president Richard Perez said Friday he was “duty bound to express my utter dismay at the grossly misleading content.”

“Conflating the campaigns and misconstruing where the listed entities designated their funds is blatantly false and offensive,” Perez wrote in a statement.

“The mail piece paid for by the police union is a disservice that uses confrontational language to confuse or merge the space between special interests and the truth. At its worst, it is a dishonest tactic that stains our system of elections.”

Police union president Mike Helle acknowledged the $3 million sum quoted in the mailer includes the Go Vote No campaign but noted Nirenberg “proclaimed himself its leader.”

“SAPOA is proud to support Greg Brockhouse for mayor and we make no secret of that fact,” Helle said in a statement. “We are glad to inform San Antonio voters of these facts (donations) because this election is not about what’s important to Ron and City Hall insiders, it’s about what’s important to San Antonio families.”

Dylan McGuinness covers City Hall and local politics in San Antonio. Read him on our free site, mySA.com, and on our subscriber site, ExpressNews.com. | dylan.mcguinness@express-news.net | Twitter: @DylMcGuinness