Joe Biden slipped in several digs at President Donald Trump without calling him out by name at John McCain's memorial service on Thursday.

The former vice president highlighted qualities of the late senator that many would not associate with the president in his eulogy.

'It wasn't about politics with John,' Biden practically shouted from the pulpit at the North Phoenix Baptist Church. 'He could disagree on substance but it was the underlying values that animated everything John did. Everything he was.'

The harsh words come as the former vice president weighs a challenge to Trump in 2002.

Joe Biden highlighted qualities of John McCain that most would not associate with President Trump in his salute to the late senator

President Trump has said Biden would be a 'dream' to run against

'Where he would part company with you was if you lacked the basic values of decency and respect, knowing this project is bigger than yourself,' Biden added loudly.

Biden's salute to McCain offered a notable contrast to Trump.

'He could not stand the abuse of power, wherever he saw it' Biden noted of McCain, 'in whatever form, in whatever country.'

'It was always about basic values with John – fairness, honesty, respect,' he added.

Biden has said he will make a decision about a 2020 presidential bid by January 2019.

The former vice president has been helping Democratic candidates in the 2018 elections, most notably giving a boost to Democratic Rep. Connor Lamb, who won a March special election in a House district that heavily went for Trump in 2016.

Biden's eulogy for McCain peppered with his folksy talk that is a Biden trademark.

Biden teared up as he remembered his longtime friend John McCain

Former Vice President Joe Biden and his wife Jill Biden pause with hands over their hearts as they watch a military honor guard place the casket of Sen. John McCain into a hearse after a memorial service at North Phoenix Baptist Church Thursday

And, at times, it sounded like something one would hear at the campaign rally.

During certain moments, the former vice president grew animated when he spoke of the current political climate, his voice growing louder and his hands waving as he defended McCain's values and decried the lack of respect seen in Washington.

McCain's own feud with Trump goes back to the roots of the 2016 presidential election. The rift between the two men was never healed.

The late senator was one of the president's harshest critics and banned him from attending his funeral.

Biden's defense of McCain's values sounded like a direct rebuke of Trump.

'John understood that America was first and foremost an idea,' he said.

Joe Biden hugs Cindy McCain after the memorial service for the late senator

President Trump with first lady Melania Trump at a reception at the White House on Wednesday

Biden and McCain served in Congress together for more than two decades, forging a friendship that withstood the test of time and brutal presidential race that pitted the senators from opposing parties against each other

And Biden railed against the tone of politics in the nation's capitol.

'All we do today is to attack the opposition in both parties – their motives, not the substance of their argument.'

Biden would likely appeal to the same blue-collar voters in Michigan, Pennsylvania, Wisconsin and Ohio that helped put Trump in the White House.

Trump, meanwhile, said in July Biden would be his 'dream' Democratic opponent in the 2020 presidential contest.

'I dream about Biden. That's a dream,' he told CBS News when asked about the next presidential election.

Then he got in a dig at the former vice president.

'Look, Joe Biden ran three times. He never got more than 1 percent and President Obama took him out of the garbage heap, and everybody was shocked that he did. I'd love to have it be Biden,' Trump said.

It's unclear what Trump meant when he said Biden ran three times. The former vice president sought the Democratic nomination in 1988 and 2008 but didn't get it on either occasion. There was speculation he would throw his hat into the ring in 2016 but he ultimately didn't run that year.