Hastert was to attend a $50-per-person fundraiser for Lewis next Tuesday in Shelby County. Lewis, a Baptist preacher and conservative Republican, is facing a spirited challenge from Democratic state Rep. Mike Weaver in Kentucky's 2nd District.
Hastert has come under attack in recent days over his handling of the complaint that Foley, a former Florida congressman, sent inappropriate e-mails to a young male page.
"I'm taking the speaker's words at face value," Lewis told The Associated Press. "I have no reason to doubt him. But until this is cleared up, I want to know the facts. If anyone in our leadership has done anything wrong, then I will be the first in line to condemn it."