WASHINGTON – Federal prosecutors investigating criminality at the Trump Organization have granted immunity to two of the president’s closest private sector allies, potentially broadening their probe into his adherence to campaign finance law in the run-up to the 2016 election.

The organization’s chief financial officer, Allen Weisselberg, and a key media ally to US President Donald Trump, David Pecker of American Media Inc., agreed to cooperate with prosecutors as part of their investigation of Michael Cohen, the president’s personal attorney of 12 years who this week plead guilty to eight felony counts of tax evasion, bank fraud and election law violations.

Cohen, a veteran of the Trump Organization, told a judge on Tuesday that he paid hush money to two of Trump’s alleged mistresses in the late hours of the 2016 race “in coordination and at the direction of a candidate for federal office,” and “for the principal purpose of influencing the election.”

The plea effectively implicated Trump in a conspiracy to break campaign finance law, raising new legal and political challenges for a president already encumbered by an investigation into his ties to Russia.

Weisselberg was the Trump Organization’s chief bookkeeper and could share with prosecutors his deep knowledge of Trump’s finances.

And Pecker, as head of the National Enquirer tabloid magazine, orchestrated an agreement with Trump that provided “trip wires” for unwanted news stories, in which his company would pay for exclusive rights to negative material on Trump and then decline to publish them.

Both Weisselberg and Pecker are mentioned in an audio recording released by Cohen’s lawyers last month, in which Cohen and Trump are discussing the hush payments to women.

While both men were granted immunity in the weeks before Cohen’s plea, they are theoretically obligated to cooperate in future related federal probes.

The rapid expansion of the campaign finance investigation, based out of the Southern District of New York, has caught the White House off guard and increased talk on Capitol Hill of impeachment – a political lightning rod entering the November midterm elections.

The case was farmed out to New York prosecutors by Special Counsel Robert Mueller III, who, in the course of his investigation of any coordination between US persons and Russia to interfere in the 2016 race, came across wrongdoing by Cohen.

Trump has increased his attacks on Mueller in recent weeks and threatened to “get involved” with the inquiry, potentially laying the groundwork for his firing of the special counsel – another potentially impeachable offense.

The US Justice Department maintains a policy that sitting presidents cannot be criminally indicted. But the constitutionality of that policy has not been ruled on by the Supreme Court; the Constitution clearly states that presidents can be indicted and sentenced after leaving office.