State Sen. Vincent Fort is running to become Atlanta's next mayor, shaking up the crowded race with a pledge to bring populist policies to the campaign.

The Atlanta Democrat, known for his biting candor and liberal views, said Thursday he's running to restore order to what he called a stagnant City Hall. He plans a formal announcement on Saturday.

"I'm running because City Hall has lost its way," said Fort. "It used to be a place that watched out for neighborhoods instead of millionaires and mega-projects."

Fort, the No. 2 Democrat in the state Senate, is a constant foil for Republicans in the statehouse. He is one of Gov. Nathan Deal's most strident critics and is among the most outspoken Democratic voices in the GOP-controlled Legislature.

He's also a thorn in the side of some of his fellow Democrats. He and Atlanta Mayor Kasim Reed, who cannot run for a third term in November 2017, can't stand each other. And Fort upset the Democratic establishment earlier this year when he announced he was flipping his support from Hillary Clinton to Vermont Sen. Bernie Sanders.

Fort joins a race that's already well underway. City Councilwoman Keisha Lance Bottoms, City Councilwoman Mary Norwood, City Council President Ceasar Mitchell, former City Councilwoman Cathy Woolard, ex- city chief operating officer Peter Aman and Reed aide Michael Sterling are among the contenders in the race.

Fort said he'll bring a Sanders-style insurgency to the race.

"This is a change election," said Fort. "And the establishment of Atlanta is the status quo. It is time for a change."