More than four in 10 Americans want the House of Representatives to begin impeachment proceedings against President Bush, and more than half want them for Vice President Cheney, a new poll shows.

In a survey of 1,100 people conducted last week by the American Research Group, 45% said they favor impeachment of the president, while 54% favor it for the vice president.

Why the difference? While the results may highlight lower public opinion of Mr. Cheney, they may also reflect a practical consideration that advocates of impeachment often point out: If Mr. Bush is removed from office through impeachment, Mr. Cheney would become president.