The presidential candidates are continuing to weigh in on the controversial Congressional practice of earmarking, in which lawmakers add provisions to appropriations bills to finance noncompetitive grants to their favored recipients, including colleges.

Yesterday Barack Obama released a list of $740-million in earmarks he requested over the past three years and challenged Hillary Rodham Clinton to do the same, according to The New York Times.

Less than one-third of his requests, about $220-million, eventually were approved, according the article. Among those that were killed was a $1-million request he made in 2006 to finance an expansion of the University of Chicago Medical Center, where his wife, Michelle, is a vice president.

Mr. Obama and Ms. Clinton, who remain locked in a fierce battle for the Democratic nomination for president, and their Republican rival, John McCain, returned to Washington this week and voted in favor of a Senate proposal to impose a one-year ban on earmarks in spending bills. The amendment failed.

Mr. McCain has been an especially ardent opponent of earmarks and has pledged to veto any bill containing them if elected president.