Former vice president Joe Biden, who appears on the cusp of running for the White House, strongly hinted Tuesday that he would launch a bid in coming weeks during an address to a conference of firefighters.

“I appreciate the energy you showed when I got up here,” Biden told a gathering of the International Association of Firefighters in Washington. “Save it a little longer. I may need it in a few weeks.”

A standing ovation ensued, with conference-goers waving “Fire Fighters for Biden” and “Run Joe Run” signs.

“Be careful what you wish for,” Biden said as the applause died down. “Be careful what you wish for.”

Though Biden has not announced his candidacy, most national polls, as well as those in early nominating states, have showed Biden leading a crowded and growing field of Democrats.

Who is hoping to challenge Trump for president in 2020?