Democratic presidential candidate Sen. Barack Obama tried to direct more than $3 million in taxpayer funds to a Chicago museum whose chairman is one of the Illinois senator’s largest campaign fundraisers.

Mr. Obama has twice since fiscal 2006 sought to have taxpayers foot the bill for a new theater projector and other equipment at the Adler Planetarium on the Lake Michigan waterfront. Neither of the requests, which totaled $3.3 million, was approved by Congress, the museum said.

The planetarium’s chairman, then and still, is Frank Clark, chief executive of ComEd, a unit of Chicago-based Exelon Energy. He has pledged to raise more than $200,000 for Mr. Obama’s run for the White House.