The Obama administration will allow tax cuts for the wealthiest Americans to expire on schedule, Treasury Secretary Timothy Geithner said Thursday, setting up a clash with Republicans and a small but vocal group of Democrats who want to delay the looming tax increases.

Mr. Geithner said the White House would allow taxes on top earners to increase in 2011 as part of an effort to bring down the U.S. budget deficit. He said the White House plans to extend expiring tax cuts for middle- and lower-income Americans, and expects to...