– Federal prosecutors unsealed charges Thursday against two men who have aided President Donald Trump's efforts to gather damaging information in Ukraine about his political opponents, a criminal case that signaled growing legal exposure for the president's allies as Trump tries to blunt an impeachment inquiry in Congress.

The indictment of the two men, Lev Parnas and Igor Fruman, sketched a complex scheme to violate campaign finance laws and did not accuse Trump of wrongdoing. But it revealed new details about the push to pressure Ukraine: a campaign encouraged by Trump, led by his private lawyer Rudy Giuliani and assisted by obscure figures like Parnas and Fruman.

Trump continues to defend the effort, which is the focus of the impeachment inquiry that House Democrats opened last month.

The new indictment, however, suggests the first criminal implications of the shadow foreign policy that Giuliani pushed on behalf of the president.

And it is another example of the extent to which the messy power dynamics of Ukraine — a former Soviet republic and close U.S. ally with a recent history of political upheaval — now dominate discussions about Trump's future.

The impeachment inquiry began after a CIA officer who has worked at the White House raised alarms about a July telephone call in which Trump sought Ukraine's help in unearthing information that could help Trump politically.

Giuliani has been public about his hunt for damaging information about Democrats, and the indictment gives a more complete picture about how he seems to have subcontracted part of the work to Parnas and Fruman, two of his longtime associates.

It directly connected the two men to a key element of the pressure campaign, an effort to recall the United States ambassador to Ukraine, Marie Yovanovitch, after she became a focus of criticism from many of Trump's allies.

Parnas and Fruman donated money and pledged to raise additional funds in 2018 — some violating legal limits — for a congressman who was then enlisted in the campaign to oust her, court papers showed.

They were charged with making illegal campaign donations, and law enforcement officials harshly criticized the scheme.

"Campaign finance laws exist for a reason," William F. Sweeney Jr., the top agent in the FBI's New York office, said during a news conference Thursday. "The American people expect and deserve an election process that hasn't been corrupted by the influence of foreign interests, and the public has a right to know the true source of campaign contributions.

"These allegations aren't about some technicality, a civil violation or an error on a form," he added. "This investigation is about corrupt behavior and deliberate lawbreaking."

The lawmaker is named in the indictment only as "Congressman-1," but campaign finance filings identify him as former Rep. Pete Sessions, R-Texas.

Sessions, then the chairman of the powerful House Rules Committee, wrote a letter in 2018 to Secretary of State Mike Pompeo saying that Yovanovitch should be fired for privately expressing "disdain" for the current administration.

Sessions, who lost his re-election bid last year, said that he could not confirm that he was "Congressman-1" but that he would "vigorously defend myself against any allegations of wrongdoing" and that he had no knowledge of the scheme detailed by prosecutors.

He said that he met the two men to discuss Ukraine's bid for energy independence and that he wrote to Pompeo "separately, after several congressional colleagues reported to me that the current U.S. ambassador to Ukraine was disparaging President Trump to others as part of those official duties."

Some Trump allies believed Yovanovitch was trying impede their effort to dig up damaging information about former Vice President Joe Biden and his son Hunter Biden, a former Ukrainian official has said, and House Democrats are looking into whether her removal was linked to Trump's attempts to gain politically helpful information.

Parnas and Fruman were arrested Wednesday evening at Dulles International Airport as they held one-way tickets to Germany.

At a hearing Thursday in federal court in northern Virginia, prosecutors argued that the men were flight risks, and a judge set bail at $1 million each.