WASHINGTON — Senator McCain, a Republican presidential hopeful, is pledging to repeal the alternative minimum tax and hold down government spending with vetoes and line-item-veto authority.

The Arizona senator, in remarks prepared for delivery yesterday evening to the Economic Club of Southwest Michigan, promised to eliminate the alternative minimum tax, which he said would affect as many as 30 million people by 2010. The tax was originally intended to make sure the wealthy do not exploit tax loopholes.

“I am committed to repealing this tax before millions of American families are forced to devote even more of their hard work to paying for the spending largesse in Washington,” Mr. McCain said in excerpts from his speech released by his campaign.

Mr. McCain said he would fight for line-item veto power, which the Supreme Court ruled was unconstitutional, but wouldn’t hesitate to use the veto as it now exists to crack down on spending.

“Give me the pen, and I’ll veto every single pork-barrel bill Congress sends me, and if they keep sending them to me, I’ll use the bully pulpit to make the people who are wasting your money famous,” he said.

Mr. McCain, long a crusader against so-called pork barrel spending, said Democrats who hold a narrow majority in Congress want to raise taxes by hundreds of billions of dollars by repealing President Bush’s tax cuts in 2001 and 2003.

Mr. McCain originally opposed Mr. Bush’s tax cuts, but he advocates extending them now because he says repealing them would amount to a tax increase. “I believe we should keep income and investment taxes low by making the tax cuts currently on the books permanent,” he said. “I think we should protect Americans from partisan Democrat tax increases.”