Former US Vice President Joe Biden speaks at the International Association of Fire Fighters conference in Washington, DC on March 12, 2019.

Former Vice President Joe Biden on Tuesday took a shot at President Donald Trump's newly unveiled fiscal 2020 budget proposal for cutting billions from federal health programs.

Biden also offered the latest — and clearest — hint that he is leaning toward a 2020 White House run, where he is already considered the Democratic front-runner in early polls.

"I was going to stay away from this, but I can't," Biden told a supportive crowd at the International Association of Fire Fighters Legislative Conference in Washington.

"Did you see the budget that was introduced? It cuts $845 billion. Almost a trillion-dollar cut in Medicare. And almost a quarter-billion [cut] ... in Medicaid," Biden said.

He continued: "Why? Because of a tax cut for the super wealthy that created a deficit of $1.9 trillion, and now they've got to make somebody pay for it."

Biden, who was vice president under President Barack Obama after a decades-long career in the Senate, launched the attack on Trump's policies just one day after the White House presented its new budget proposal, which administration officials say will tackle excessive government spending and U.S. deficits.

The plan would cut an estimated $800 billion or more over 10 years from the 65-and-up Medicare, according to reports and analysis from the Kaiser Family Foundation. The proposal would also reduce spending on Medicaid, the federal-and-state program that provides low-income Americans insurance, by more than $200 billion while setting up block grants to states.

The White House denies that Trump's budget cuts the perennially popular Medicare program. Acting Budget Director Russ Vought said Monday that Trump is "not cutting Medicare in this budget" but rather "putting forward reforms that are cutting drug prices."

The budget would also allocate $8.6 billion toward the construction of Trump's long-promised border wall.

At the firefighters' event Tuesday morning, Biden also teased his plans about running for president on the Democratic ticket in the 2020 election.

"I appreciate the energy you showed when I came up here. Save it a little longer — I may need it in a few weeks." Biden said to raucous applause from the crowd, which later broke into chants of "run, Joe, run!"

"Be careful what you wish for," he quipped a moment later.