U.S. Republican presidential hopeful Rudy Giuliani, a survivor of prostate cancer, tried to allay concerns about his health after a hospital stay he attributed to a painful headache.
His staff originally said the former New York mayor had flu-like symptoms when he ordered his plane back to St. Louis last week but he cited a "headache worse than I've ever had."
Giuliani, 63, left the hospital on Thursday after an overnight stay just weeks before Jan. 3, when Iowa begins the state-by-state nominating process to choose the Republican and Democratic candidates in the November 2008 election.
"I feel great now, I feel terrific. I've been tested out, everything came back 100 percent," Giuliani said in a taped interview with ABC News' "This Week" program. Giuliani, back on the campaign trail on Sunday in New Hampshire, said his doctor would address the episode after Christmas.
"There's always the issue of cancer, so I'm going to have him put out a statement and then, you know, make everyone really comfortable that I'm OK," Giuliani said. "But they tell me I'm in very good health."
Giuliani's battle with prostate cancer prompted him to drop out of the 2000 Senate race in New York against Hillary Clinton, then the first lady and now a front-runner for the Democratic presidential nomination.
Giuliani, who plays heavily on his leadership role in New York after the Sept. 11 attacks by al Qaeda militants in 2001, insisted he was clear of cancer.
In New Hampshire's Jan. 8 primary, Giuliani is fighting to keep up with former Massachusetts Gov. Mitt Romney and Sen. John McCain of Arizona, who won important newspaper endorsements last week that invigorated his campaign.
Giuliani has trailed in opinion polls in Iowa and New Hampshire -- whose early contests can give a crucial boost to presidential candidates -- but has led national surveys of Republican voters.
A poll published by the Boston Globe on Sunday showed McCain closing on Romney in New Hampshire with support of 25 percent of Republican voters versus Romney's 28 percent.
The survey, which had a margin of error of 4.9 percentage points, showed Giuliani slipping from second place in New Hampshire last month into third, with 14 percent support.
Among Democrats, Illinois Sen. Barack Obama -- striving to be the first black U.S. president -- was gaining on Clinton in New Hampshire, with 30 percent to her 28 percent.
That was a big shift from a Globe survey last month when Clinton, who has comfortably led her rivals in national polls, had a 14-point advantage in the state. Former North Carolina Sen. John Edwards remained a steady third at 14 percent. Clinton, aspiring to be the first woman U.S. president, flew from New Hampshire to Iowa in a snowstorm to make a last pitch to voters before a two-day Christmas break.
She was to join her husband, former President Bill Clinton, for a church service before they campaigned separately throughout the state.
Obama was campaigning in western Iowa on Sunday, while Edwards left for North Carolina to begin his Christmas break.