WASHINGTON (AP) _ Bob Squier, a Democratic media consultant whose work for presidential candidates from Hubert Humphrey to Bill Clinton helped transform the way political campaigns are waged, has died at age 65.

He had been battling colon cancer. President Clinton remembered Squier's ``path-breaking political commentary'' as an analyst on NBC's ``Today'' show and his work for progressive candidates. ``I owe him much,'' he said.

``Throughout the course of his career, Bob was a pioneer in the art of political communications,'' said Clinton. ``Bob helped make policy and politics understandable and exciting for millions of Americans.''

An award-winning documentary filmmaker, Squier's first presidential campaign work was for Hubert Humphrey in 1968. He made spots for Ed Muskie in 1972 and Jimmy Carter in 1976. He was an architect of the Clinton-Gore re-election media strategy in 1996.

Along the way, Squier had a hand in transforming advertising's role in campaigns.

A professional partner, Bill Knapp, said Squier was ``a groundbreaking political consultant'' and credited him with helping to create the modern campaign.

``In this business, you're kind of really judged by the number of wins you have by your name, and no one had more than him,'' said fellow consultant James Carville. ``He was to political consulting what Hank Aaron was to home runs.''

Squier had a reputation for hard-hitting spots, and was at times accused of crossing the ethical line.

In 1990, one Squier spot charged a gubernatorial candidate in Massachusetts was ``plagued by questions about his corruption record'' _ the questions were about the candidate's record in prosecuting official wrongdoing. Another Squier spot accused a Michigan candidate of voting ``to let dangerous criminals out of state prisons early'' when Squier's client had put the same early release program into effect.

Yet Squier was an advocate of greater media scrutiny of the claims made by political advertisers.

``You've just got to be much tougher with people like us as we make our spots and advance our claims,'' he told reporters at a 1988 forum.

Squier created ads for dozens of campaigns for the Senate, the House and governorships. He was part of Clinton's creative team in 1992, and was a close friend of Vice President Al Gore.

Gore's office released a statement from the presidential candidate that called Squier ``one of the most talented and dedicated advisers the Democratic Party has ever had.''

Last year, Squier's role in the Gore presidential campaign was curtailed when Carter Eskew, an estranged Squier protege, was brought on board to help with his media strategy.

Eskew and Squier had a bitter falling out over problems related to their shared consultancy a half-dozen years earlier, and the bad blood generated headlines when they were brought back together.

Squier sought to put an end to the intrigue. ``The bottom line on this is we are already working together with the common goal of getting Al Gore elected president,'' he said.

In addition to his political work, Squier won awards for his documentaries, including films on William Faulkner and Herman Melville. He was working on a piece about Ernest Hemingway.

Squier leaves his wife, Prudence, and two sons.