Washington ? A former House clerk faces investigators today in possibly the most important testimony yet on how GOP leaders dealt with allegations about ex-Rep. Mark Foley’s behavior toward pages. That includes their secret handling last fall of a complaint to a congressman who testified Wednesday.

The questioning of the former clerk, Jeff Trandahl, is coming after Rep. Rodney Alexander, R-La., spent three hours with ethics investigators. He sought to explain how his office dealt with the complaint from a former page about too-friendly e-mails from Foley.

GOP leaders are facing scrutiny over whether they or their aides did too little to stop Foley’s inappropriate behavior toward pages when problems surfaced years ago. The revelations have been followed by weakening poll numbers for Republicans, who insist that no one in their party knew of the sexually graphic e-mails that have scandalized the public.

Trandahl’s testimony is critical in determining how many people knew about Foley’s behavior with pages and whether there are even more incidents than those reported so far.

Alexander discussed the matter last spring with two top House GOP lawmakers, Majority Leader John Boehner of Ohio and campaign chair Tom Reynolds of New York, both of whom say they spoke with House Speaker Dennis Hastert about it. Hastert, R-Ill., has said he does not recall the conversations.

Trandahl confronted Foley, a Florida Republican, last fall over his e-mails to the Louisiana boy and was alerted about inappropriate e-mails Foley sent in 2001 or 2002 to a former page sponsored by Rep. Jim Kolbe, R-Ariz.

As the House officer with direct responsibility for the page program, Trandahl is virtually certain to know whether there have been other complaints about Foley, including an alleged incident in which the Florida Republican tried to enter the page dorm while drunk.

The panel is trying to determine whether lawmakers and staff aides acted properly when alerted about Foley’s behavior. Trandahl’s testimony is crucial to knowing how many people knew about the page issue – and how problems with Foley were handled – before the scandal exploded last month.

Foley resigned from the House on Sept. 29 after being confronted with sexually explicit messages sent in 2003 to a former Oklahoma page.

Trandahl is in position to support testimony by Kirk Fordham, a former top aide to Foley, who has told the ethics panel that he informed top House GOP aides of Foley’s inappropriate behavior toward pages years ago. Fordham has testified he told senior House staff aides about the page dorm incident when it happened several years ago.

A key issue is whether staff aides to Hastert knew about Foley’s improper behavior before the 2005 episode and whether they told Hastert – who says he knew nothing about Foley and pages prior to the day Foley resigned.

In the 1990s, Trandahl worked with the office of then-Rep. Pat Roberts, R-Kan. He served as the clerk of the House of Representatives from 1998 until 2005, when he resigned to accept a position as the executive director of the National Fish and Wildlife Foundation.