Mayor de Blasio’s re-election campaign begged supporters on Saturday to send him cash, blaming President Trump in part for a recent fundraising advantage held by his GOP opponent — who said the desperate plea is proof Hizzoner is “running scared.”

The mayor’s missive moaned that the national GOP, along with “President Trump’s massive email list” have forced him to play catch-up in the fundraising department as his campaign rolls into the home stretch.

“We’re going to make a real push to match her spending in the final weeks of the campaign,” his email promised, along with a request for contributions as low as $5.

“Now his campaign is asking for $5 donations? How sad,” sniffed Republican challenger Assemblywoman Nicole Malliotakis, who collected $107,566 to the mayor’s $83,414 from Sept. 19 through Oct. 2, according to reports last week.

She added: “His fundraising is dropping off because of his failed policies and weak debate performance.”

With nearly 40 percent of her haul coming from small donors, Malliotakis is eligible to collect an additional $246,000 in matching funds from the city.

But de Blasio still has plenty of cash to burn in the last three weeks of his re-election effort. His campaign had $2.3 million in the bank at the end of the most recent reporting period, compared to just $760,000 for Malliotakis.

Both campaigns are pouring money into TV ads. The mayor’s first general-election spot began airing Saturday.

Malliotakis spokesman Rob Ryan denied that her campaign has tapped Trump resources.

“That’s a bit of an exaggeration,” Ryan said, “We’re getting as many lists as we can, including one from the Republican National Committee.”

A Quinnipiac poll released Oct. 5 had de Blasio with huge leads over the three other candidates vying for City Hall, with 61 percent of likely voters in his corner and just 17 percent for Malliotakis.

The Reform Party’s Sal Albanese pulled in support from 8 percent of voters and independent candidate Bo Dietl 6 percent.

Malliotakis, who said in September that her internal polling revealed a closer race, pointed to the fundraising results as an indicator of a heated contest.

“New Yorkers from all five boroughs are contributing to my campaign because they want a subway system that works, a solution to the homeless crisis and schools that educate and are safe,” she told The Post. “If I was Bill de Blasio I’d be worried too.”

A de Blasio spokesman did not immediately return a request for comment.