The Senate Judiciary Committee has subpoenaed Paul Manafort to testify in public

The Senate Judiciary Committee issued a subpoena to President Donald Trump's former campaign chairman, Paul Manafort, on Tuesday to compel him to testify before the committee in an open session Wednesday.

"While we were willing to accomodate Mr. Manafort's request to cooperate with the committee's investigation without appearing at Wednesday's hearing, we were unable to reach an agreement for a voluntary transcribed interview with the Judiciary Committee," committee chairman Chuck Grassley and ranking Democrat Dianne Feinstein said in a statement.

"Mr. Manafort, through his attorney, said that he would be willing to provide only a single transcribed interview to Congress, which would not be available to the Judiciary Committee members or staff," they continued. "While the Judiciary Committee was willing to cooperate on equal terms with any other committee to accomodate Mr. Manafort's request, ultimately that was not possible."

The committee is examining Manafort's financial history and past work for a pro-Russian political party in Ukraine as part of its investigation into Russia's election interference.

The topic for Wednesday's hearing is the Foreign Agents Registration Act - a law passed in 1938 requiring that US citizens representing the interests of foreign powers in a "political or quasi-political capacity" disclose that relationship.

On March 22, The Associated Press reported that Manafort was paid $10 million between 2006 and 2009 to lobby on behalf of Russian billionaire Oleg Deripaska, a close Putin ally. The New York Times reported recently that Manafort was indebted to pro-Russian interests as late as last year. Investigators are also probing whether Manafort engaged in money laundering, according to The Wall Street Journal.

Grassley and Feinstein wrote that the committee "may be willing to excuse [Manafort] from Wednesday's hearing if he would be willing to agree to production of documents and a transcribed interview." But such an interview would not "prejudice the committee's right to compel his testimony in the future," they said.

The committee has also subpoenaed Glenn Simpson, the cofounder of opposition research firm Fusion GPS, to compel him to testify publicly on Wednesday. Simpson's lawyer said compelling his client to appear at the FARA hearing was "a pretext for an exploration of Fusion GPS' reported work, on behalf of other clients, to investigate the ties of Donald J. Trump, his campaign and their associates to Russia."

Simpson hired former British spy Christopher Steele last year to research Trump's ties to Russia at the request of anti-Trump Republicans. Democrats took over funding for Steele's project after Trump won the Republican nomination.