Biden drops hint on 2020: Save your energy 'I may need it in a few weeks'

There was no 2020 announcement from former Vice President Joe Biden Tuesday but he dropped a big hint at what might be coming and when.

Biden was greeted at the International Association of Fire Fighters legislative conference with chants of “Run Joe Run,” as audience members waved gold and black signs reading “Fire Fighters for Biden” and “Run Joe Run,” leaving little question about who'd they'd support if he does enter the race.

“I appreciate the energy when I got up here. Save it a little longer -- I may need it in a few weeks,” Biden said Tuesday at the event in Washington, D.C.

Biden has been connected with the influential union for more than 40 years. After his comment about a possible 2020 bid received rousing applause, he added, “Be careful what you wish for!”

IAFF General President Harold Schaitberger told reporters after the event that the union was ready to stand with Biden if he decides to enter the race.

“He's getting ready to make an important decision and I made sure he knew that when he's ready to pull the trigger, so are we,” Schaitberger said.

A source close to Biden said he hasn't made a decision yet, but once one is made, an official announcement would still be a few weeks off.

People who have spoken with Biden in recent weeks tell ABC News he is ‘90 percent there’ on a run for the presidency.

While leaving a separate event in Washington Tuesday, ABC asked Biden what the holdup was on making a decision about 2020.

“No hold up —- the car’s working!” Biden joked, as he got into a waiting car, and drove off flashing a smile and waiving.

ABC News' Mary Bruce and John Verhovek contributed to this report.