A high-profile Washington, D.C., defense attorney will represent former U.S. House of Representatives Speaker Dennis Hastert on criminal charges he tried to hide $3.5 million in payments he was making to conceal past misconduct, the attorney's law firm confirmed on Monday.

Thomas Green of Sidley Austin will represent Hastert, 73, according to Carter Phillips, chair of Sidley's executive committee. The former lawmaker will be arraigned on Tuesday in U.S. District Court in Chicago, the court's website says.

Green has represented clients tied to the Whitewater and Iran-Contra investigations, according to the Sidley Austin website. A 2003 national poll conducted by the "Corporate Crime Reporter" newsletter named Green as one of the top five white collar defense attorneys in the United States, the website said.

Green declined to comment on the charges.

Hastert has made no public statement since the federal charges were filed late last month. He left Congress in 2007 after eight years as House Speaker, the longest time a Republican has held the powerful political post.

According to the indictment, Hastert structured the withdrawal of $952,000 in cash to evade a requirement that banks report cash transactions over $10,000 and then lied to the Federal Bureau of Investigation about the withdrawals.

The indictment said Hastert agreed several years ago to make a total of $3.5 million in payments to an individual to compensate for and conceal past misconduct. Several media outlets have cited law enforcement officials who said the past misconduct was sexual and dated from Hastert's time as a teacher and sports coach at Yorkville High School in rural Illinois.