No, the pardon power is broad and absolute. You don't even need to be charged. The only limitation known is that you can't pardon future crimes. That would be a carte blanche, and it isn't a part of english common law, which is where the definition of a pardon originated.
Remember Richard Nixon? Gerald Ford pardoned him before any charges were brought.
President Ford issued a presidential pardon (Proclamation 4311) on September 8, 1974, which granted former president Richard Nixon a full and unconditional pardon for any crimes he might have committed against the United States while president (Wikipedia).
But it looks like we will need another yes vote to convict. This one doesn't look very certain.
Manchin goes full MAGA
Source:
Politico
The vulnerable West Virginia Democrat is embracing Donald Trump, figuratively and literally: ‘We just kind of do the man-bump type thing.’
By BURGESS EVERETT 06/06/2018 04:02 AM EDT
RANSON, W.Va. — Joe Manchin wants you to know he really likes Donald Trump.
The West Virginia senator doesn’t put it quite that way. But more than any other Democrat in Congress, he's positioned himself as a vocal Trump ally. In fact, the senator, up for reelection in a state Trump won by more than 40 points, told POLITICO he isn’t ruling out endorsing Trump for reelection in 2020 — a position practically unheard of for a politician with a “D” next to his name.
“I’m open to supporting the person who I think is best for my country and my state,” Manchin said this week from the driver’s seat of his Grand Cherokee, insisting he’s game to work with any president of either party. “If his policies are best, I’ll be right there.”
Trump’s popularity in West Virginia has Republicans salivating over the prospect of knocking off the legendary 70-year-old senator and former governor this fall. In response, Manchin is sidling up to the president — his policies, his nominees, at times even Trump himself — as the independent-minded Democrat prepares for the toughest race of his career against GOP state Attorney General Patrick Morrisey.
Read more:
https://www.politico.com/story/2018/06/06/manchin-trump-west-virginia-midterms-626437