Hillary Clinton is hoping the "Colbert bump" will help propel her to victory in Pennsylvania.The Democratic presidential candidate will make her first appearance on Comedy Central's "The Colbert Report" on Thursday. Both Clinton and Colbert have come to Pennsylvania ahead of the state's hard-fought Democratic primary on April 22. Clinton rival Barack Obama (web|news|bio) also is in Pennsylvania, but has thus far declined Colbert's invitation. Obama's wife, Michelle, will appear on the show Tuesday.

News of Clinton's visit was divulged Monday night in Philadelphia by MSNBC pundit Chris Matthews. He blurted it out during taping of the show at the University of Pennsylvania's Zellerbach Theater. The news was confirmed by a person close to the satirical news program, who insisted on anonymity because the date of the visit hadn't been publicly announced.

Comedy shows have played a role in the presidential campaign, and good things have happened to guests on "Colbert." Former Arkansas Gov. Mike Huckabee was a regular on the show before his unexpected - but short-lived - success in pursuing the Republican nomination. And a "Saturday Night Live" sketch was credited for helping Clinton gain momentum in February.