Sen. George Voinovich surprised a lot of people in Washington by bucking the White House and speaking out against the appointment of John R. Bolton as U.N. ambassador.

Those who have followed the Republican over his nearly 40 years in Ohio politics were not among them.

''They're not seeing the new Voinovich. They're seeing the real Voinovich,'' said William Binning, chairman of the political science department at Youngstown State University.

Voinovich's blast of Bolton during Thursday's meeting of the Senate Foreign Relations Committee earned daylong coverage on the news networks and the top of Page One in many newspapers, including The New York Times. No Ohio senator has made this kind of splash since Democrat John Glenn returned to space in 1998 at age 77.

In an impassioned voice, Voinovich questioned the impact on the United Nations of President Bush's appointment of an ambassador ''who himself has been accused of being arrogant, of not listening to his friends, of acting unilaterally and of bullying those who do not have ability to properly defend themselves.''

He called Bolton ''the poster-child of what someone in the diplomatic corps should not be'' but refused to block a vote by the full Senate.

Binning, a Republican, worked on Voinovich campaigns from his 1978 election as lieutenant governor to his gubernatorial elections in the 1990s. He said showing a controlled independent streak was vintage Voinovich.

''In terms of just his general behavior, he doesn't go looking for trouble, but when he decides something, he's like granite,'' Binning said.

Over his career, Voinovich hasn't hesitated to speak out against fellow Republicans if he disagrees with them. As mayor of Cleveland in the 1980s, he clashed with President Reagan over cuts to local governments. Two years ago, Voinovich was one of two Republicans who promised to vote against any tax cuts over $350 billion. Bush had proposed $726 billion in cuts, but Voinovich and Maine Sen. Olympia Snowe prevailed.

Voinovich, 68, occasionally shows an emotional side. Speaking with reporters in 1992 as he watched demonstrators outside his Statehouse window protesting welfare cuts, Voinovich said, ''Whether they believe it or not, George Voinovich really cares for his fellow man. That's why I'm in the business. I'm doing the best I can with what I've got.'' His voice faltering, he broke into tears.

At a fundraiser for now-Attorney General Jim Petro in 2002, Voinovich praised the job Bush was doing with ''the fullest plate'' of any president, with war in Afghanistan and the yet-to-come war in Iraq. ''Your senator is very concerned about our great country,'' Voinovich said, his voice cracking.

Voinovich also has showed anger. As governor in 1995, Voinovich's state plane was grounded for a trip to Canton while President Clinton was in Columbus. He grabbed the pilot's microphone, uttering obscenities, and told the control tower that the Secret Service could ''shoot us down'' and ordered the pilot to take off. He paid a $1,500 fine to the Federal Aviation Administration. He later said, ''I should have exercised more restraint, not lost my temper.''

James Ruvolo, a Toledo Democrat who has worked on dozens of campaigns since the 1970s, said Voinovich's statements Thursday showed his stubbornness and anger. Ruvolo pointed out that Voinovich sides with the GOP party line most of the time.

''He climbs out on a limb. Sometimes he stays there, sometimes he climbs back,'' Ruvolo said. ''The Republicans have been very good at getting people get back on the reservation in time.''

Voinovich aide Marcie Ridgway said Friday that calls to his office since the Bolton statement have been mostly supportive. Voinovich realized the response he would get would be mixed, she said.

''This was really a thoughtful process for him and he went in there and did what he thought was right,'' Ridgway said.

John McCarthy is a correspondent for the Ohio Associated Press.