Sometimes, it takes a fund-raiser.

State Treasurer Bob Casey traveled to Chicago yesterday to take advantage of some campaign cash assistance from Sen. Hillary Clinton, D-N.Y.

The former first lady, author and likely 2008 presidential candidate was the featured attraction at a $500-a-ticket reception for Mr. Casey's bid to unseat Republican Sen. Rick Santorum.

The New York senator was in Chicago to give a speech on the economy. Larry Smar, Mr. Casey's press secretary, declined to estimate how much the campaign expected to reap from the event.

The title of Mr. Santorum's book, "It Takes a Family,'' was a tacit rebuttal to the message of Ms. Clinton's book, "It Takes a Village,'' which was published while she was first lady.

Virginia Davis, a spokesman for Mr. Casey's anticipated opponent, criticized the joint appearance.

"While Rick Santorum is teaming up with folks like Rudy Giuliani and John McCain to help with his re-election, Bobby Casey is skipping work to campaign with the likes of Hillary Clinton and Howard Dean. We'll take that match-up any time,'' Ms Davis said.

Mr. Santorum and Mr. Casey are locked in a financial as well as a political battle in a Senate race that is expected to be among the most watched and most expensive in the country.

At the end of 2005, the incumbent had $7.8 million in cash on hand while the Democrat had $3.4 million. At that point, Mr. Santorum was one of the leading fund-raisers among incumbents and Mr. Casey was at the top of the list of Senate challengers. By November, according to some projections, combined spending in the race could surpass $40 million. Updated figures on their fund raising for the first quarter of the year are due to be reported at the end of the week.