Sen. John McCain called yesterday for the federal government to suspend gasoline taxes from Memorial Day to Labor Day this year to force down fuel prices and pump money into the economy.

The proposal was McCain's main message during a day of campaigning in Pennsylvania that also included another attempt to explain his comments over the winter in New Hampshire that U.S. troops might have to stay in Iraq for perhaps a century.

"I said maybe 100 [years] - after the war is over," he said at Villanova University, where for an hour he appeared live on MSNBC's

Hardball

show.

Earlier, at Carnegie Mellon University in Pittsburgh, the presumptive Republican presidential said of his gas-tax proposal: "The effect will be an immediate economic stimulus - taking a few dollars off the price of a tank of gas every time a family, a farmer, or trucker stops to fill up."

The plan to suspend the 18.4-cents-a-gallon tax, which McCain called "a gas-tax holiday," topped a package of economic proposals unveiled by the Arizona Republican.

The package included some ideas long dear to Republicans, including a flat-tax option to the federal income tax and a presidential line-item veto.

McCain reiterated proposals to lower business taxes, raise the dependent-child tax credit from $3,500 to $7,000, and permanently lock in President Bush's tax cuts, enacted by Congress from 2001 to 2003. McCain opposed the tax cuts until his campaign for the presidency.

He also proposed requiring affluent people - couples making more than $164,000 - enrolled in Medicare to pay a higher premium for prescription drugs.

Addressing worries that college students might get shut out of education loans this fall because of the credit squeeze caused by the housing-loan crisis, McCain said the Department of Education should work with governors "to make sure that each state's guarantee agency has the means and manpower to meet its obligation as a lender-of-last-resort for student loans."

The Republican candidate's Pennsylvania visit diverted some attention from what has been an all-consuming political story in the Keystone State - the Democratic presidential primary, set for a climax six days from today.

He criticized both Democratic contenders, Sens. Hillary Rodham Clinton and Barack Obama, contending that they would let the Bush tax cuts expire out of concern that they benefit the wealthiest Americans. McCain said that letting the cuts expire would amount to the single largest tax increase since World War II.

"They're going to raise your taxes by thousands of dollars per year - and they have the audacity to hope you don't mind," he said, alluding to the title of one of Obama's books,

The Audacity of Hope

.

McCain's proposals drew attacks from the Obama and Clinton campaigns. Obama spokesman Bill Burton tied the proposals to what he called "George Bush's failed policies." He called the tax cuts irresponsible.

Clinton policy director Neera Tanden said the "tax cuts for the wealthy . . . will bankrupt our government and leave working families with the bill."

Some economists expressed skepticism about McCain's economic plan.

McCain is "talking about huge tax cuts and just a little about spending cuts," said economist Gus Faucher of Moody's Economy.com in West Chester. "And that means he's talking about a substantially larger deficit."

Commerce Bank chief economist Joel Naroff questioned the wisdom of formulating economic and tax policies that would take effect months or years from now.

Doubling the deduction for dependents "is appealing to families," he said, but "if it happens, it's likely to hit at a time when we may not need it."

Naroff also said that relative to the full pump price of motor fuel, elimination of the 18.4-cent tax per gallon doesn't amount to much in savings: "It's better than nothing, but not a whole lot better than nothing."

The gas-tax suspension proposal clearly was the highlight of McCain's plan and likely to be the most debated in the next weeks. He also renewed a call to stop making oil purchases for the Strategic Petroleum Reserve Fund, to cut demand.

The Associated Press quoted McCain aides as saying his Senate staff was drafting a bill on the gas-tax-holiday proposal, which is likely to face strong opposition in Congress and from the states.

The federal gasoline tax covers the lion's share of the costs for highway and bridge projects across the country - revenue that states would have trouble making up, even if lost for a short term.

McCain said losses to the treasury could be offset by cuts in "wasteful spending."

During his

Hardball

appearance, McCain said of the American presence in Iraq that he envisioned a situation like that in South Korea, where U.S. troops have been stationed for 55 years, since the end of the Korean War, without major casualties.

The crowd at the Pavilion basketball arena, often boisterous, especially with every mention of Villanova, fell silent as McCain defended his position on keeping troops in Iraq for decades more to guarantee stability there.

McCain noted that America's continued presence in South Korea has not been unpopular. "Americans were fine with that because it provided security," he said.

He drew applause from the several thousand students and others when he said that if he were elected president, the United States would "never again torture another person" in the war on terrorism.

In the spirit of the moment, he noted he was in the Philadelphia area and said to

Hardball

host Chris Matthews: "Can I ask you a question first? Cheesesteaks - Pat's or Geno's?"

Matthews, who grew up in the Philadelphia area, knew better than to choose.

"Take your chances," he said.

Contact staff writer Tom Infield

at 610-313-8205 or tinfield@phillynews.com.

This article contains information from Inquirer staff writer Tony Gnoffo and the Associated Press.