Sen. John McCain (Ariz.) may return to Capitol Hill this month to support an amendment imposing a one-year ban on earmarks, a move that could set up a divisive clash within the GOP caucus.

McCain, the likely Republican presidential nominee, has long broken with most of Congress, including the Senate Republican leadership, in seeking an end to the practice of inserting line items in spending bills for parochial projects.

McCain told conservative bloggers on a conference call this week that – if his schedule permits – he would take a break from the campaign trail and vote on an amendment by Sen. Jim DeMint (R-S.C.) to impose a one-year ban on earmarks.

“I absolutely would support such an amendment – and abolish [earmarks] altogether,” McCain said, according to the Red State blog. “As I’ve said, I will veto any earmark project that comes across my desk.”

McCain is highlighting his opposition to earmarks as a way to appease conservatives skeptical of his candidacy because of other issues, such as his support for a legalization program for illegal immigrants and campaign finance restrictions and his initial opposition to President Bush’s tax cuts. On the stump, he has criticized his Democratic opponents, Sens. Barack Obama (Ill.) and Hillary Rodham Clinton (N.Y.), for individually securing almost $4 million and $100 million, respectively, for pet projects in the fiscal 2008 spending legislation enacted in December.

McCain, who secured no pet projects in the recent spending law, calls them a waste of taxpayer dollars.

“I really can’t tell you, traveling and campaigning now for many months, how dispirited the Bridge to Nowhere or earmark and pork-barrel spending was to our Republican base,” he said on this week's conference call. “We lost in 2006 not because of Iraq but because spending got out of control.”

DeMint plans to offer his amendment to a fiscal 2009 budget resolution that Democrats plan to bring to the floor on the week of March 10. That same week, a GOP task force convened by Senate Minority Leader Mitch McConnell (R-Ky.) is expected to offer its recommendations on how to reform the earmarking practice.

Sen. Richard Lugar (Ind.) is chairing the GOP task force, whose members also include Sens. Thad Cochran (Miss.), Mike Crapo (Idaho), Tom Coburn (Okla.) and Johnny Isakson (Ga.). The members have been meeting weekly, but Republican aides doubt that the group will recommend eliminating earmarks. Cochran, the Appropriations Committee ranking member, is one of the most notorious earmarkers in Congress, while Coburn has sided with DeMint and McCain on the issue.

A McConnell aide said the Republican leader probably wouldn’t take a position on the DeMint measure until after the GOP task force issues its recommendations. According to Taxpayers for Common Sense, McConnell secured $126 million in individual earmarks in the recently enacted spending law; his deputy and Arizona Sen. Jon Kyl earmarked $2 million; the third-ranking Senate Republican leader, Lamar Alexander (Tenn.), inserted $6 million individually; GOP Policy Chairwoman Kay Bailey Hutchison (Texas) racked up almost $42 million in projects; and Conference Vice Chairman John Cornyn (Texas) got $14 million.

If McCain returns and lobbies his members to support an amendment that the leadership opposes, it could test rank-and-file members to support either their nominee or their Senate leaders.

“McCain is a Senate reformer who’s locked horns with our leadership for years,” a GOP aide said. “But now he’s our nominee and the old bulls will have to decide if their pork is more important than our party’s future.”