WAKE FOREST - Politics at the pump dominated the Democratic presidential primary race Saturday, with Sen. Hillary Rodham Clinton pushing for a federal gas tax holiday -- and criticizing Sen. Barack Obama for failing to do so.

Clinton crisscrossed North Carolina -- from Cary High School to the North Carolina Auto Racing Hall of Fame in Mooresville -- drawing sharp distinctions between herself and Obama on several issues.

But she reserved some of her most pointed language for her proposal to suspend the federal gas tax over the summer, a move that she said would save the average American $70, even more for truckers, farmers and those with long commutes. She said the oil companies could be made to pay for the lost revenue.

Obama, campaigning in Indianapolis, was quick to respond, saying the proposal symbolizes "phony ideas, calculated to win elections instead of actually solving problems."

The sharp exchange underscored the tightening primary Tuesday in North Carolina and the high stakes in one of the closest presidential contests in recent memory.

With North Carolina suddenly in play, the Clintons planned to blanket the state, and both campaigns used phone banks, automated calls, the Internet, mail and e-mail to mobilize thousands of supporters. Both spent large sums on television advertising.

On Saturday, only Hillary Clinton worked the state. Obama was in Indiana, where some polls show the two running evenly.

"There is a big disagreement in this campaign about where Senator Obama and I stand about taking on the immediate crisis that we confront," Clinton told several hundred people standing in front of a museum in Wake Forest, a picturesque old college town. "My opponent is running ads and holding press conferences attacking my plan to try to give you some kind of break this summer."

She said she would ask the the Justice Department and Federal Trade Commission to investigate price manipulation by the oil companies.

"Demand it, demand it," shouted Julius Morris, a 58-year old Wake Forest resident who helps build broadcast towers.

Missouri Sen. Claire McCaskill, campaigning for Obama in North Carolina on Saturday, called the proposal a political ploy.

"The gas tax holiday that has been proposed by Sen. Clinton and Sen. [John] McCain doesn't make sense to most North Carolinians on any level," McCaskill said. "It's a little insulting that anybody could think they could get a vote for less than a half of a tank of gas. There is no assurance that this gas tax holiday would mean any real savings for any families in North Carolina. Just because you take a hit off the top of gas taxes doesn't mean the prices will go down."

McCaskill estimated that the holiday would save the average family $28.

She also noted that North Carolina Gov. Mike Easley, who stumped at Clinton's side Saturday, had dismissed in May 2006 a gas tax holiday as "a subsidy for the oil companies."

Heightened rhetoric

Clinton drew unflattering distinctions between her and Obama's positions on gas taxes and the mortgage crisis, and on their leadership experience. It was her sharpest criticism of Obama while campaigning in North Carolina, and came one day after Obama stepped up his criticism of her at the Democrats' annual Jefferson-Jackson Day Dinner.

"I know the difference between between making speeches and implementing solutions," Clinton said.

The tougher rhetoric comes as Obama's once-strong lead has been dwindling in North Carolina. A new tracking poll by Zogby shows the presidential race continuing to tighten here.

Zogby surveyed 627 likely Democratic primary voters May 1-2, and found that Obama was the choice of 46 percent. Clinton was the choice of 37 percent; 9 percent were not sure. The margin of error was plus or minus 4 percentage points.

The same poll found that 19 percent of likely Democratic primary voters would defect to Republican John McCain in the general election if Obama is the Democratic nominee. If Clinton is the nominee, 17 percent said they would support McCain.

McCaskill said she was not surprised that the race is getting closer here.

"The Clintons have paid a lot of attention to North Carolina," McCaskill said. "President Clinton has camped out in North Carolina -- it feels like."

Pre-primary momentum

Former President Clinton is scheduled to return today for a 15-town, two-day swing. Hillary Clinton was planning to return to North Carolina on Monday as the Clinton campaign continued to turn up the heat here.

"I'm impressed with her stamina in the last couple of weeks," said Shaunesy Story, a 35-year old paralegal from Mebane who was at Clinton's event in Cary. "She is showing North Carolina what she is capable of."

Added Karen Dash, a 42-year old analyst from Pittsboro, said: "She and her husband are the ultimate comeback kids."

After attending Saturday's Jefferson-Jackson Day dinner in Raleigh on Friday night, Obama returned to Indiana, which is holding a primary on the same day as North Carolina. Michelle Obama, his wife, is scheduled to return to the state Monday.

At Cary High School on a panel hosted by the Web site momlogic.com, Hillary Clinton engaged in some lighthearted banter about raising families. She was asked about her daughter Chelsea's early dating experiences when she was living in the White House.

"Chelsea was a teenager in the White House, which meant that the Secret Service went on her dates," she said. "A lot of her girlfriends' mothers loved it when they double dated, because there was a guy with a gun in the front seat."