Des Moines, Iowa ? Democrats swapped last-minute charges of smear tactics Saturday as polls pointed to the closest Iowa caucus finish since the event gained presidential campaign prominence in the 1970s.

“I’m in full combat mode,” said Howard Dean, delivering a self-appraisal that applied no less to Dick Gephardt, John Kerry and John Edwards as they charged across the state on the race’s final weekend.

The charges of distortion and malicious phone calls contrasted sharply with efforts by the candidates to sound a softer closing note in first test of the campaign season.

Kerry held an emotional reunion with a fellow Vietnam veteran whose life he saved in combat 35 years ago. “He could have been shot and killed at any time,” said Jim Rassmann. “I figure I owe him my life.”

Dean, Edwards and Kerry all invoked the ghosts of Franklin Roosevelt, Harry Truman and John Kennedy during the day, vying for acceptance as the one rightful political heir to past Democratic presidents.

The final television commercials were upbeat, as well, including one from Edwards that relied on the written word — rather than the spoken one — to make its point. “To all those who stood up, listened and spoke out. Made us laugh, question, think and believe a positive vision of hope and new ideas can change America. Your time is now,” rolled across the screen.

But the campaign niceties seemed to end there.

Kerry, who has gained ground in recent polls, said Dean and Gephardt were trying to dampen his momentum in the agriculture-conscious state with a “smear effort” that distorted his record on farm issues. On Friday, the two rival campaigns provided reporters with comments Kerry made five years ago, indicating he would scale back the Department of Agriculture and revamp farm subsidies.

Kerry said during the day he would revamp the subsidy program, not end it. But Erik Smith, a spokesman for Gephardt, dismissed the charge, adding the Massachusetts senator has “been sending negative mail on Gephardt for weeks.”

Kerry’s campaign, too, stood accused of unsavory campaign practices. Aides to Dean said at least one of their voters had received a badgering phone call from a Kerry supporter who called the former Vermont governor an “environmental racist.”

Stephanie Cutter, a spokeswoman for Kerry, said the call was an “isolated incident” caused by overzealousness on the part of a young volunteer. She said he had been asked to leave the campaign, and was writing a letter or apology to the woman he called.

Neither side seemed willing to let it drop, though.

“This kid’s supervisor made no apologies for his phone call. Nor did that supervisor’s supervisor,” said Trish Enright, spokeswoman for Dean.

Kerry’s aides provided a supporter who said she had received a similar phone call from a Dean volunteer. “I said, ‘I don’t need to put up with this and I hung up,” Leslie Sheeder said in an interview.

Aides to Edwards said an undisclosed number of their supporters had received 2 a.m. telephone calls in recent days, informing them they were ineligible to vote.

The Monday night caucuses will set the party on a path to selecting a challenger for President Bush this fall.

That made Bush a spectator with an unusually personal interest in the outcome, and he was maneuvering for advantage already.

Tuesday night’s State of the Union message assured him of massive media coverage, in time to quickly dim any glow that the Democratic caucus winner receives.

GOP aides said Bush would use his speech to argue that he had made Americans more prosperous and secure, citing the rising stock market, the growing economy and Saddam Hussein’s capture.

Whichever Democrat challenges him will have a contrary argument to make — the worst job-creation record since Herbert Hoover, record deficits and a death toll of at least 500 in Iraq.

Before any of them could concentrate on Bush, however, there was Iowa, kickoff contest in the battle for the nomination. Statewide polls suggested a tight four-way finish Monday night, when caucus-goers gather in 1,993 precincts in every corner of the state. That would make it the closest contest since it achieved prominence in 1976. That was the year Jimmy Carter finished behind uncommitted but ahead of his rivals, a showing that launched him on the road to the White House.

After Iowa, the campaign moves to New Hampshire, where retired Army Gen. Wesley Clark is coming under close scrutiny because of his surge in statewide polls. Wading into perilous political territory, Clark told a voter in Laconia, N.H., that one reason New Hampshire property taxes are high is the state has no income or general sales tax.

Although Clark is skipping the Iowa caucuses, he dispatched an advance scout. “I’m just checking things out,” said Bill Buck, a aide who attended one of Kerry’s campaign appearances.

All four of the major rivals made multiple stops during the day — Gephardt made seven as he struggled to avoid a loss that aides said could spell the end of his political career.