Undated (AP) _ Dianne Feinstein, savoring success in California's Democratic primary for governor, embarked on her fall campaign today against well-financed GOP rival Pete Wilson. North Carolina Democrats picked a black man to try to dethrone GOP Sen. Jesse Helms.

In the longest count of a nine-state primary election, Alabama Attorney General Don Siegelman squeezed into a runoff for the Democratic nomination for governor with teacher lobbyist Paul Hubbert after an all-night vote tally. The winner of the June 26 balloting will face GOP Gov. Guy Hunt.

Seven senators gained nominations for new terms. GOP Sen. Thad Cochran of Mississippi was arguably the biggest winner among them. He faces no Democratic opposition in the fall and is thus assured of a new term.

Democrats Bill Bradley of New Jersey, Howell Heflin of Alabama and Max Baucus of Montana easily overcame challenges within their party, while Democrat Tom Harkin of Iowa and Republicans Larry Pressler of South Dakota and Pete Domenici of New Mexico were unopposed.

Incumbent governors in Iowa and South Dakota also were renominated, along with Hunt in Alabama.

In California, both Feinstein and Wilson, a second-term senator, were kicking off their fall campaigns with breakfast appearances.

''Whoop it up tonight because this is your last victory party of the 1990s,'' Wilson told the Democrats late Tuesday night after breezing to his nomination.

Democratic national chairman Ron Brown hailed Feinstein's success and called the defeat of two Republican-backed redistricting referenda a ''blowout for us.''

''They are going to have a money advantage,'' he said, referring to Wilson's $3 million warchest. But, he added, ''issues are going to prevail.''

It was the California Democratic primary for governor that drew most of the nationwide attention, both for the size of the state and because the next governor will play a large role in determining which party benefits from a census that may increase the state's congressional delegation by a half-dozen seats.

''One mission completed, one to go,'' former San Francisco Mayor Feinstein told supporters after securing her victory in a hard-fought primary.

With 99 percent of the precincts counted, she had 52 percent of the vote, to 41 percent for Attorney General John Van de Kamp. Nine other candidates split the remaining votes.

Wilson breezed to an easy primary victory on the GOP side, and said he'd keep the governor's office in Republican hands. He decided to run for the job when GOP Gov. George Deukmejian declined to seek a third term.

Feinstein praised Van de Kamp in her victory speech and said the fall campaign will be a choice between two Californias. ''One ... with a declining quality of life, more crime, more traffic ... It is content with caretaker government,'' she said. ''But our California is a ... bold place.''

In North Carolina, Helms congratulated Harvey Gantt on ''a hard-earned victory.''

''How sweet it is,'' a jubilant Gantt told supporters after dispatching prosecutor Mike Easley with 57 percent of the vote. His victory made him the first of his race to win a Senate nomination this century in North Carolina.

''I want to tell you that God is good, yes he is. It's a new day in North Carolina,'' said Gantt, a former mayor of Charlotte.

Alabama boasted the closest race of the night, a Democratic primary to pick an opponent for incumbent GOP Gov. Guy Hunt.

Education Association lobbyist Hubbert and Siegelman claimed the right to face off in the runoff. With 96 percent of precincts reporting, Hubbert was winning 32 percent of the vote and Siegelman 25 percent, followed by former Gov. Fob James with 22 percent and Rep. Ronnie Flippo 17 percent. Two other candidates trailed.

''This is no place for the faint-hearted,'' said Flippo as the long count continued.

In an Iowa primary contest viewed as a referendum on abortion, House Speaker Don Avenson claimed the Democratic nomination for governor against GOP incumbent Terry Branstad, who opposes abortion. Avenson, who favors abortion rights, won 40 percent of the vote to defeat anti-abortion Democrat Tom Miller and three other contenders. The National Organization for Women and the National Abortion Rights ActionLeague, both of which endorsed Avenson, had feared he would split the vote with other pro-choice contenders and permit Miller to win.

In addition to picking candidates for governor, Californians voted to raise the state gasoline tax from 9 to 18 cents a gallon to finance badly needed highway repair. Supporters said approval of the measure would mark a symbolic end to the tax revolt that began in 1978 with passage of Proposition 13. With 98 percent of precincts counted, the proposal was gaining 52 percent of the vote.

The lines were drawn for what shape up as some of the nation's most contested Senate elections in November, when Republicans seek to cut into the current 55-45 Democratic advantage.

Republicans count Harkin as among the most vulnerable Democrats, and Rep. Tom Tauke has been campaigning against him even in advance of formally claiming the GOP nomination Tuesday night.

Republicans profess hope for knocking off two-term Democrat Max Baucus in Montana, as well. The victor in a four-way GOP race was Lt. Gov. Allen Kolstad, who entered the race at the urging of the national Republican leadership.

In New Jersey, Christine Todd Whitman was unopposed for the GOP nomination to oppose Bradley. In Alabama, state Sen. Bill Cabannis had no GOP opposition for the chance to challenge Heflin.

GOP Sen. Domenici in New Mexico will face Democratic State Sen. Tom Benavides, who was unopposed for his party's nomination.

On the other side of the aisle, Democrats eye Pressler of South Dakota as a potential victim for the fall. Ted Muenster, who had no primary opposition, will run against him.

In New Mexico's governor's race, former Gov. Bruce King won the Democratic nomination in a bid to regain the office he's held for eight years - longer than anyone in state history. Former state Rep. Frank Bond won the Republican nomination. Each man defeated three rivals.