New Jersey Gov. Chris Christie. (Photo by Michael Loccisano/Getty Images)

Maryland Gov. Martin O’Malley (D) inserted himself into the New Jersey governor’s race on Monday, knocking Republican incumbent Chris Christie for vetoing legislation last year that would have allowed same-sex marriages in the Garden State.

“Christie vetoed a marriage equality bill last year, denying thousands of New Jerseyans equality,” O’Malley said in a fundraising solicitation on behalf of Democratic gubernatorial hopeful Barbara Buono. “We have a chance to defeat him and make real progress, but we need you today!”

Christie has pushed instead for a voter referendum on the issue of gay nuptials.

He has been a frequent target for O’Malley, the former chairman of the Democratic Governors Association who is considering a 2016 presidential bid. In speeches to Democratic audiences around the country, O’Malley has often held Christie up as an example of Republican governors pursuing misguided policies on a range of issues.

In the letter seeking money for Buono, a state senator, O’Malley said he “was honored to lead the fight for dignity and equality in Maryland.”

Last year, lawmakers passed a bill sponsored by O’Malley legalizing same-sex marriage. The legislation was petitioned to the ballot in Maryland by opponents and narrowly survived in November.

David Ferguson, executive director of the Maryland Republican Party, said he was not impressed by O’Malley’s fundraising solicitation.

“Unfortunately, he keeps playing national politics rather than doing his job here in Maryland,” Ferguson said. “Governor Christie has been a real leader for New Jersey, and his approval ratings show it.”

A poll released last month by Kean University showed 70 percent of New Jersey voters approved of Christie’s job performance.

That’s a good bit higher than the number O’Malley received in a Washington Post poll published in March: 49 percent of Marylanders approved of the job O’Malley was doing as governor.