In his rapid rise to power in the Senate, Trent Lott employed every resource at his disposal: relentless ambition, hard work, luck, cunning, Southern collegiality, sharp elbows, a penchant for order and a self-confidence that stands out even by Senate standards. Even so, his base of support has always been shaky, broader than it was deep.

During a decade in the Senate leadership, Lott's breadth of backing has been the key to his success, combining enough moderates with his conservative base to ensure a majority in the GOP caucus and fend off potential rivals.

But now it is the depth -- or shallowness -- of that support that is likely to determine whether the 61-year-old Mississippi Republican will survive a crisis of his own making: his declaration Dec. 5 that the country would have been better served if Strom Thurmond had been elected president on a segregationist platform in 1948. The result has been a firestorm within the country and the GOP that threatens the political career Lott has taken three decades to build.

Lott was never the first choice of either ideological flank of the Senate GOP, relying instead on his ability to bridge the gap between them by embracing conservative positions while cutting the deals needed to keep the Senate running. Conservatives complained he was too ready to deal; moderates wanted more deals. Although he has loyalists who are working to keep him as leader, Lott has never inspired the kind of fierce personal devotion enjoyed by former House speaker Newt Gingrich (Ga.), who led the victorious Republican "revolution" in 1994. But even Gingrich was forced to step down in the wake of a scandal that threatened his party and his colleagues. Some have suggested it is possible that no one -- not even an iconic leader -- could withstand the trouble that Lott has heaped on himself.

"There's no such thing as a Lott Republican," said John J. Pitney, a political science professor who monitors Republican politics at Claremont McKenna College in California. "He has personal friends but he doesn't have people who will walk through [fire] for him. Unless you have a strong personal base of support, people will leave you alone on the battlefield."

Current and former colleagues speak more of his personal attributes than passion among followers. "He's aggressive, he's intense, he's goal-oriented," said former senator Alan K. Simpson (R-Wyo.), a moderate whom Lott unseated as Republican whip in 1994. "He loves the job, not the perks of leadership but the power of leadership, the ability to . . . say what needs to be done and get it done."

Robert J. Dole (Kan.), Lott's predecessor as Republican leader, appeared to inspire more personal loyalty, Pitney and others said, but he also drew heavier fire from conservatives. .

Lott's rise to power in the Senate actually began before he even got there. Not long after he was elected to the Senate in 1988, he invited reporters to his office in the House, where he had served for 16 years, rising to the post of whip, the No. 2 Republican leadership position. What did he want to do when he got to the Senate, he was asked. Get into the leadership as soon as possible, he responded. At the time, he had not even been sworn in as a senator.

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In addition to ambition and hard work, Lott benefited from a generational and ideological shift in the party. Power was moving to the right and toward the South, and he was there to seize it, beating everyone else to the gate. Moreover, many prominent Senate Republicans, such as Richard G. Lugar (Ind.), incoming chairman of the Foreign Relations Committee, have found job satisfaction elsewhere.

In his 6 1/2 years as the Senate's top Republican, Lott has sometimes played the staunch conservative, sometimes the more pragmatic legislative matchmaker, often angering one wing or another of his caucus but stopping short of creating a crisis that could endanger his career.

At times, conservatives tried to get Sen. Don Nickles (R-Okla.), the party's No. 2 leader and a more ideologically inclined conservative, to challenge Lott. But Nickles declined, apparently for lack of votes from senators who regarded him as too ideologically conservative. Moderates, already frozen out of the leadership, gave up trying.

Lott had blowups from time to time with president Bill Clinton and Daschle, but working relationships were never totally broken. And, on major issues, such as the balanced-budget effort in 1997, the chemical weapons treaty of that year and a carefully drawn scenario for the Clinton impeachment trial in 1999, Lott usually opted for compromise over confrontation, risking a backlash from his conservative wing.

More often than not, Lott has walked a fine line, sometimes stumbling. When he cut deals with the Democrats on spending and other flash-point issues, conservatives accused him of selling out. When he refused to do so, Democrats accused him of partisanship and obstruction.

As a leader, Lott has been especially attentive to other senators' personal and political needs, ranging from highways and bridges to protection from potentially injurious votes, according to other Republicans. "I've been in meetings where a broader issue is being discussed and he would say, 'Hey, this won't work because Senator X has a problem with his ranchers on it,'" a Senate Republican aide recalled.

Lott's style of leadership also has been characterized by his penchant for order, discipline and punctuality, which are not among the characteristics usually ascribed to the free-wheeling Senate. A fastidious dresser who never has a hair out of place or a scuff on his shoes, Lott has been consumed from the start with trying to get the Senate to shape up. "Regular order!" which members of Congress call out when they want the rules to be followed, became the mantra of his leadership.

Colleagues laughed at his efforts to get people to stay in designated crosswalks around the Capitol but were quietly relieved when he tried to get members home in time for dinner. Lott has gotten the Senate to move a little more crisply, but his tenure as majority leader has been marked by some of the most paralyzing partisan warfare in memory.

"He was a very orderly man in a disorderly body," said Ross K. Baker, a political science professor at Rutgers University in New Jersey.

Lott's low point -- until now -- came when he did not head off, and may have contributed to, the defection of Vermont Sen. James M. Jeffords from the GOP in June 2001, giving Democrats control of the narrowly divided Senate until the Republicans took it back in last month's elections. The moderate Jeffords felt squeezed out of the party and appeared to blame the White House and Lott.

Even some party conservatives blamed Lott for not stopping the Jeffords defection, accusing him of the same kind of maladroit performance that he made in trying to recover from the Thurmond remark. "For some things, Trent has a tin ear," a friend said.

Ironically, according to critics as well as allies, Lott probably was never more secure in his job than he was only three weeks ago. Republicans had just reelected him by acclamation as their leader, and many believed his tactics in the final days of the 107th Congress put Democrats on the defensive and helped elect a Republican majority in November.

"He was on a roll," said an aide to another GOP senator. Then Lott made his tribute to Thurmond, a Republican senator from South Carolina, and, in a second, his base crumbled. Senate Republicans have scheduled a meeting for Jan. 6, the day before the 108th Congress will convene, to consider whether to stand by Lott or elect a new leader.

In the past few years, Lott has lost some of his closest friends and allies in the Senate -- including Paul D. Coverdell (Ga.), who died; Slade Gorton (Wash.), who was defeated, and Dan Coats (Ind.) and Connie Mack (Fla.), who retired. But Lott associates say he has stronger support in the Senate than many outsiders realize. "This is why it's not over yet," a Republican aide said.

Researcher Lucy Shackelford contributed to this report.

Former House speaker Newt Gingrich enjoyed a greater level of fierce loyalty than Trent Lott does.