The controversy could have serious fallout for the Republican party in the November elections, as it puts in jeopardy another Republican seat in the House of Representatives, where Democrats need only 15 to retake control.
The FBI is determining whether there has been any violation of federal law involving Mark Foley of Florida, who resigned amid allegations he sent inappropriate messages to young people working at the US Congress.
House of Representatives Speaker Dennis Hastert, Republican of Illinois said he was told of the situation some six months before Foley resigned.
He’s written to US Attorney General Alberto Gonzales requesting a Justice Department investigation of Mr Foley's conduct with current and former teens who work for the House as part-time interns, or pages.
Top House Republicans acknowledged yesterday they had been aware of email traffic between Mr Foley and a former teenage page, but that they were not aware of the sexually explicit messages to other pages revealed last week.
The six-term Florida Republican resigned after US media reports that he sent messages containing references to sexual organs and acts to current and former congressional pages.
Democrats demand answers
House Democratic leader Nancy Pelosi said House Republican leaders should be questioned under oath on how much they knew of Foley's emails to male pages, the teenagers who answer telephones, deliver documents and run other errands for members of Congress.
Mr Foley was chairman of the House caucus on missing and exploited children, and the author of the key sexual predator provisions of the Adam Walsh Child Protection and Safety Act of 2006, which Bush signed in July.
Senate Democratic leader Harry Reid of Nevada said the attorney general should open a "full scale investigation immediately."
He said in a statement that the allegations were "repugnant, but equally as bad is the possibility that Republican leaders in the House knew there was a problem and ignored it to preserve a congressional seat this election year."
Democrats and at least one Republican said House Republican leaders should step down if they were aware that Foley was sending inappropriate messages and did nothing about it.