Look out, Washington. Oprah Winfrey is set to unleash the force of her powerful media empire on Congress when she attempts to mobilize her followers on Monday to press for the passage of a Senate bill battling child exploitation.

Winfrey thrust herself into the middle of the presidential race last year when she endorsed Barack Obama, a first for the queen of daytime talk. Now she's throwing her support behind a bill that is sponsored by Obama's running mate, Joe Biden, and opposed by a Republican senator who is an ardent supporter of John McCain.

The bill would increase resources for regional computer forensic labs and add other improvements to increase the ability of authorities to investigate and prosecute predators.

Oklahoma Sen. Tom Coburn, a Republican, opposes the Biden bill because he says he wants to stop redundant programs and reduce federal spending. The bill also is caught up in a larger fight with the Senate Democratic leadership.

Senators' offices received an automated e-mail warning Friday to beware of a possible increase in traffic on the Senate's Web site.

"We have learned that Oprah Winfrey will be urging viewers to contact their senators to support S.1738, the Combating Child Exploitation bill," on her Monday show, the notice reads, explaining that she will provide a link to www.senate.gov on her Web Site, www.oprah.com.

"We anticipate larger than normal volumes of traffic on senate.gov and increases in e-mail and Web form mail to member offices as a result of this effort."

In recent weeks, Winfrey has drawn criticism for not inviting Republican vice presidential nominee Sarah Palin on her show, saying she would consider it after the election. Obama has appeared on Winfrey's popular daytime show twice — in early 2005 and the fall of 2006 — before he was a presidential candidate.

"At the beginning of this presidential campaign when I decided that I was going to take my first public stance in support of a candidate, I made the decision not to use my show as a platform for any of the candidates," Oprah said in a statement released when the criticism started.

Child exploitation has emerged as a campaign issue. McCain just released an ad condemning what he said was an Obama vote for "comprehensive sex education" for kindergartners. But the bill, which never passed the Illinois state Senate, actually outlined age-appropriate categories, seeking to teach young children how to defend themselves against sexual predators and inappropriate touching.