WASHINGTON - US President Barack Obama's new Afghanistan surge drew a wary welcome from lawmakers worried about prospects for winning the war and how the cash-strapped superpower will pay the bill.

Obama's Republican foes warily pledged support for his plan to send 30,000 US soldiers at a cost of about 30 billion dollars this year, while some of his Democratic allies warned ramping up the conflict would prove an epic blunder.

"I support the president's decision," said Republican Senate Minority Leader Mitch McConnell, who has thrown up roadblocks against the president's agenda at every turn since Obama took office in January.

But this time "hopefully he'll have good support across the board," said McConnell, who underlined that lawmakers who control the US purse strings must "provide every resource necessary to prevail."

Democratic Senate Majority Leader Harry Reid crowed that Obama "will finally give this mission the attention and resources it demands" while underlining that "our commitment is not open-ended." But others bluntly dissented.

"I do not support the president's decision to send additional troops to fight a war in Afghanistan that is no longer in our national security interest," said Democratic Senator Russell Feingold.

Feingold, who had vowed earlier to consider blocking funding for the escalation, called Obama's plan "an expensive gamble," vowed to pursue his efforts to set a flexible timetable for withdrawal from Afghanistan.

In general, Republicans worried about Obama's goal of beginning a drawdown in July 2011, warning Afghans would turn away from US-led forces if they doubted Washington's commitment.

Many Democrats, meanwhile, worried that the new mission lacked a precise set of benchmarks to measure progress and said they wanted more details about how quickly key goals could be achieved ? hastening the return home of US troops.

As details of the plan leaked out hours before the speech, lawmakers wrestled with how to pay for the expansion of the eight-year-old war at a time when the White House forecasts a whopping 1.5-trillion-dollar fiscal deficit in 2010 and the national debt has reached a record 12 trillion dollars.

"We can't simply afford to ignore the price of these wars," Obama said in his speech, vowing to "work closely with Congress" as it confronts the titanic bill for the conflicts in Iraq and Afghanistan.

Lawmakers wondered aloud what approach to take: Repurpose unspent economic stimulus funds? Levy a special tax? Issue war bonds like those that fueled the US military effort in World War II? Spending freezes?

"There isn't any miraculous way to pay for it," said Democratic Senator Ben Nelson, who told reporters he liked war bonds because "I start off thinking that we'd be better off to borrow from ourselves than to borrow from China."

Democratic Representative Dave Obey, the powerful chairman of the House Appropriations Committee, warned the Afghan war could cost 90 billion dollars in 2009 and pushed for a special tax, chiefly on the richest Americans.

"If this endeavor is to be pursued, we must have a renewed sense of shared sacrifice," said Obey.

"You're not going to raise taxes in the midst of a downturn, that just doesn't make good economic sense, but at the same time this needs to be paid for over time," said Democratic Senator Kent Conrad, chairman of the Senate's budget committee.

Obama's 2008 rival for the White House, Republican Senator John McCain, called for freezing discretionary government spending at 2009 levels and predicted this would yield about 60 billion dollars.

McConnell said unspent funds in the 787-billion-dollar economic stimulus package approved in early 2009 would be "a good place to look."

Democratic Senator Byron Dorgan said while he does not have a favorite among the plans, "we've been adding to the charge card" to fight the war "and that's irresponsible."