Republican mayoral challenger Paul Massey raised double the haul of incumbent Democrat Bill de Blasio — $850,000 compared to $394,000 — over the latest two-month reporting period, according to the campaigns.

Massey, a multimillionaire real estate executive, is hoping to unseat de Blasio by focusing on corruption probes of the mayor by state and federal prosecutors. De Blasio maintains his innocence, and no one has been charged with any crime.

“I will do whatever it takes to win this election, to ensure our children, seniors and most vulnerable are given more importance than the special interests, and most important, bring back integrity to City Hall,” Massey said in a statement.

De Blasio highlighted the large number of small donations in an email to supporters.

He said he had more than 3,000 donations, 95 percent of which came from “working people,” many $175 or less.

“What this report proves is that when you put working people first in your work and in your campaign, they will respond by stepping up and supporting those efforts,” he said.

Massey on Wednesday visited a charter school; de Blasio held town-hall-style meetings by phone and in Chelsea.

Under New York City’s strict campaign finance law, campaigns are required to report how much they raise to election regulators at various points over the year. The official numbers weren’t immediately available.