ALEXANDRIA, Va. — A federal judge on Friday asked pointed questions about special counsel Robert Mueller's authority to bring charges against former Trump campaign chairman Paul Manafort and suggested that prosecutors' true motive is getting Manafort to "sing" against the president.

Manafort's lawyers argued at a hearing in Alexandria that the tax and bank fraud charges are far afield from Mueller's mandate to investigate Russian meddling in the 2016 election and whether any coordination with Trump associates occurred.

"I don't see what relationship this indictment has with what the special counsel is investigating," U.S. Senior Judge T.S. Ellis III, a Reagan appointee, told government lawyers at Friday's hearing.

The Virginia indictment alleges Manafort hid tens of millions of dollars he earned advising pro-Russia politicians in Ukraine from the Internal Revenue Service, money earned from 2006 through 2015. The indictment accuses Manafort of fraudulently obtaining millions in loans from financial institutions later, after his Ukrainian work dwindled. Prosecutors say that part of the conspiracy stretched from 2015 through January 2017, including the months while he was working on the Trump campaign.

Under questioning from Ellis, government lawyers admitted that Manafort had been under investigation for years in the Eastern District of Virginia before Mueller was ever appointed special counsel. And Ellis said it was implausible to think that the charges against Manafort, which primarily concern his business dealings and tax returns from about 2005 through 2015, could have a real connection to Trump's 2016 presidential campaign.

Ellis suggested the real reason Mueller is pursuing Manafort is to pressure him to "sing" against Trump, though he also noted that such a strategy is a "time-honored practice" for prosecutors and not necessarily illegal. Ellis went on to say that defense lawyers are naturally concerned that defendants in that situation will not only sing but "compose" — meaning that they'll make up facts.

"You really care about wanting information you could get from Mr. Manafort that would relate to Mr. Trump and lead to his prosecution, or impeachment, or whatever," Ellis said.

Later Friday, President Trump praised Ellis during a speech to the National Rifle Association and called him a "highly respected judge." Trump read news articles highlighting Ellis' quotes about the case and his suggestion that the special counsel's goal is to squeeze Manfort. "I've been saying that for a long time," Trump said.

At the hearing, government lawyer Michael Dreeben responded to Ellis that the special counsel's mandate is broad, and that Manafort fits within that jurisdiction because of his connections to both the Trump campaign and to Ukrainian and Russian officials.

"We needed to understand and explore those relationships and follow the money where it led," Dreeben said.

Dreeben also argued that the Justice Department has broad discretion to set its own rules for what should be designated to the special counsel's jurisdiction, and that a judge has no role trying to regulate it.

"We are the Justice Department," Dreeben said of the special counsel's office. "We are not separate from the Justice Department."

That argument provoked Ellis' ire to an extent and prompted him to question the wisdom of granting unfettered power to a special counsel with a $10 million budget.

"I'm sure you're sensitive to the fact that the American people feel pretty strongly about no one having unfettered power," Ellis said.

He asked Dreeben whether the special counsel had already blown through its $10 million budget; Dreeben declined to answer.

Manafort's lawyer, Kevin Downing, has argued that a special counsel should be tightly constrained in how it operates. He noted that the law authorizing the special counsel was passed to replace the old independent counsel law, which was derided for allowing overbroad, yearslong investigations during the Reagan and Clinton administrations.

Downing has argued that the charges should be dismissed if Mueller lacked authority to bring them. Ellis, though, suggested another remedy would be to simply hand the case back to regular federal prosecutors.

Ellis withheld ruling on the motion and will issue a written ruling at a later date.

Manafort is also facing a separate indictment in the District of Columbia, where the special counsel has brought the bulk of charges. Prosecutors also wanted to bring the Virginia charges in the District of Columbia, arguing it would be more efficient. But Manafort had the right to have the case heard in Virginia, because that is where the alleged misconduct in the Virginia indictment occurred. Manafort declined to waive his right to have the charges adjudicated in Virginia.

Manafort's lawyers made similar arguments seeking dismissal to the judge overseeing the District case. She has also not yet ruled on the motion.