St. Petersburg mayoral challenger Rick Kriseman has picked up another big endorsement.

Former Florida Gov. Charlie Crist publicly endorse Kriseman on Monday. The state's former Republican governor may be a candidate for the office again next year as a Democrat.

"I have seen Rick Kriseman in action on important issues and he was effective," Crist said on Monday. "He brought people together from both parties to solve problems and pass important legislation. When some Tallahassee politicians and interest groups wanted to allow risky oil drilling off our beautiful coast, Rick Kriseman led the charge against it, protecting our economy, environment and quality of life.

"Rick Kriseman has articulated a strong, clear vision for this city with new ideas to save money and to attract and keep high tech and clean energy jobs. Rick Kriseman is a good person and he’ll make a great mayor."

Kriseman, 51, a former lawmaker in the Florida state House, is locked in a close race with Mayor Bill Foster.

Prominent Democrats Florida Sen. Bill Nelson and former Chief Financial Officer Alex Sink also have backed Kriseman. Florida Gov. Rick Scott has endorsed Foster.

A poll conducted a few weeks ago by the Tampa Bay Times and Bay News 9 showed Kriseman ahead by the slimmest of margins, with 40 percent of the vote compared to Foster's 39, well within the poll's margin of error of 4.8 percentage points.

Election Day is Nov. 5.