Republican nominee and pork buster John McCain will take a break from the campaign trail tomorrow to vote on an amendment to the Senate’s budget resolution. The amendment would impose a one-year ban on earmarks in congressional spending bills.

Mr. McCain, an ardent opponent of earmarking – the practice of providing noncompetitive grants to colleges and other recipients – has pledged to veto any bill containing earmarks if elected.

The amendment, which will be offered by Sen. Jim DeMint, a Republican of South Carolina, is opposed by Senate Democratic leaders, who have said it would be unrealistic to impose a one-year moratorium on earmarks. They point out that Congress has already passed legislation placing new restrictions on earmarks and adding transparency to the earmarking process.

But the amendment appears to be gaining some steam. Democratic presidential candidates Hillary Rodham Clinton and Barack Obama signed on as cosponsors yesterday, after Mr. McCain issued a press release calling on them to lend bipartisan support to the amendment. Supporters need 60 votes to secure the amendment’s addition to the Senate’s budget blueprint for fiscal 2009.

Mr. McCain, who clinched the Republican nomination last week after winning primaries in Texas, Ohio, Vermont and Rhode Island, is in New Hampshire today for a town hall meeting and will be in Pennsylvania for a similar meeting on Friday.