WASHINGTON - A day before he is scheduled to announce a new strategy in Afghanistan, President Obama is under increasing pressure to explain how his administration intends to pay the rising costs of military operations in Afghanistan, which average about $3.6 billion per month.

US soldiers patrol the site of a suicide attack in Kabul. US President Barack Obama is grappling over whether to send more US troops to Afghanistan to boost the fight against a growing Taliban-led insurgency. (AFP/File/Massoud Hossaini) Both Republicans and Democrats pressed the issue yesterday, previewing the political minefield that Obama will face when he addresses the nation from West Point tomorrow. Key Republicans said they intend to support him on his expected plan to send more troops, but called on him to curb domestic spending on items they oppose.

"Can we trim up the health care to fight a war that must be won?'' asked Lindsey Graham of South Carolina on ABC's "This Week.'' He also suggested rethinking the stimulus payments sent to states to help jump-start the economy.

Richard Lugar of Indiana, the ranking Republican on the Senate Foreign Relations Committee, made similar remarks, signaling that Obama's strongest backers on the war would use the opportunity to oppose him on other issues.

"The war is terribly important,'' Lugar told CNN's "State of the Union.'' "Jobs and our economy are terribly important. So this may be an audacious suggestion, but I would suggest we put aside the health care debate until next year, the same way we put cap-and-trade and climate change, and talk now about the essentials: the war and money.''

Obama is expected to send about 30,000 additional troops to Afghanistan, slightly fewer than the 40,000 that the NATO commander in Afghanistan, General Stanley McChrystal, requested.

White House budget director Peter Orszag, who has attended at least one of Obama's war strategy meetings, has suggested that the cost of 30,000 additional troops would be roughly $30 billion a year, or $1 million per fighter. But some budget analysts believe the cost would be closer to $800,000 per fighter, and because Obama intends to phase the new troops in over a period of 18 months, few analysts think the costs would be that high.

Still, many Democrats continued to express misgivings about deepening the US commitment in Afghanistan, with some arguing that if more troops must be sent overseas, the administration should be forced to levy a special war tax to pay for them.

Representative David Obey, a Wisconsin Democrat and chairman of the House Appropriations Committee, introduced legislation last week that would implement a graduated tax in 2011 on income to pay for the nation's wars, starting at 1 percent for the low-income bracket, and rising to 5 percent for the wealthiest.

"If this war is important enough to engage in long-term, it's important enough to pay for,'' Obey said on "State of the Union'' yesterday. "In this war we have not had any sense of shared sacrifice. The only people being asked to sacrifice are military families.''

Few Democrats have gone as far as Obey to press the administration to devise an immediate payment plan for the war, a move that critics say is simply a way of opposing a troop increase. But other Democrats signaled that questioning costs would continue to be a major strategy for skeptics of the war.

"We're engaged in a huge debate on health care and central to that debate is paying for it,'' Senator Jack Reed, a Rhode Island Democrat, told CNN. "If we're paying for the health and welfare of the American people, we certainly have to pay for our operations overseas.''

Senator Carl Levin, the Michigan Democrat who chairs the Senate Armed Services Committee, said yesterday that it would not be possible to increase taxes on the middle class in the midst of the worst recession since the Great Depression, but that the nation's wealthiest could be asked to pay more.

"There should have been, as far as I'm concerned, tax increases long ago on upper-bracket folks who did so well during the Bush years,'' he told CBS's "Face the Nation,'' a reference to the Bush administration's decision to lower taxes on the wealthy, while borrowing money to finance two wars.

"That should have happened some time ago,'' Levin said. "But in the middle of this recession I don't think you're going to be able, successfully or fairly, to add a tax burden to middle-income people.''

Partisan wrangling aside, the cost of the war in Afghanistan has become an increasing focus of the American public.

Chris Helman, director of research at the National Priorities Project, a Northampton-based national organization that calculates the costs of the nation's wars, says that 2.5 million people each month log on to view the group's steadily increasing "cost of war'' clock at www.costofwar.com.

"As wars grow in their duration, costs become an increasing concern, particularly when you see an erosion of public support,'' Helman said.

The clock, based on figures obtained from the Congressional Research Service, a nonpartisan research arm of Congress, shows that the United States has spent more than $937 billion on the wars in Afghanistan and Iraq since 2001, roughly the same amount that health care bills in Congress are expected to cost over a period of 10 years.

The bulk of the war costs - $704 billion - was spent on Iraq, while just $232 billion was spent on Afghanistan. But next year, for the first time ever, Afghanistan is slated to be more costly than Iraq.

The Pentagon has requested $130 billion for the two wars in 2010, about $65 billion for Afghanistan and $61 billion for Iraq, where troops are due to begin coming home.

That budget request included the deployment of the 21,000 additional troops that Obama ordered to Afghanistan this year, but not the 30,000 additional troops that he is expected to announce tomorrow.

Even the most optimistic budget estimates predict that the US government will spend hundreds of billions more on the wars in Iraq and Afghanistan, even if they draw to a close in coming years. Helman said the costs are likely to be financed as they were under the previous administration, by borrowing.

"At the end of the day, they are just going to borrow more money,'' he said.