CHICAGO, MARCH 15 -- House Ways and Means Committee Chairman Dan Rostenkowski (D-Ill.) easily won his Illinois Democratic primary contest tonight with a surprisingly strong showing that was cheered as much in the White House as it was at Rostenkowski campaign headquarters here.

With 95 percent of the precincts reporting, Rostenkowski led his nearest rival, state Sen. John Cullerton, by 50 percent to 30 percent of the vote. Dick Simpson, a college professor and former Chicago alderman who won 43 percent of the vote in the 1992 primary against Rostenkowski, was running third with 14 percent. Two minor candidates accounted for the rest.

In an emotional appearance before supporters tonight, Rostenkowski said those who voted for him "believe that action is more important than words. They believe that government in Washington can work and must work."

Then, directly addressing those who voted against him, Rostenkowski added, "You must understand that politics is not a profession that rewards purity or perfection. It is about consensus and compromise, two values that I treasure. The critics say that I'm not perfect and they're right. I've made mistakes. I hope I've learned from them and will do better in the future than I've done in the past."

Rostenkowski also recalled "a pivotal moment in the campaign when a very, very gutsy and honorable and courageous man named Bill Clinton came to town. I'm proud to be a soldier in the president's army for change."

The victory left Rostenkowski in place as one of Clinton's most important and powerful allies on Capitol Hill for the upcoming battle over health care legislation and other key administration initiatives.

But his win tonight did not end Rostenkowski's problems, the most important of which is a two-year federal grand jury investigation in Washington that is focusing on his alleged role in the House Post Office scandal. Under House rules, if he is indicted he would be forced to resign as chairman, although he would remain a member of the Ways and Means Committee.

But even an indictment might not be fatal for Rostenkowski in the November general election in the overwhelmingly Democratic congressional district.

In the Democratic gubernatorial contest, state Comptroller Dawn Clark Netsch, 67, defeated the one-time front-runner in the race, Attorney General Roland W. Burris. With 93 percent of the precincts reporting , Netsch had 45 percent to Burris's 35 percent. Another candidate, Cook County Board President Richard Phelan, was a distant third.

Netsch's victory made Illinois history, marking the first time a woman has been nominated for governor. But she will be an underdog in the general election against Gov. Jim Edgar, who easily won the Republican gubernatorial primary over conservative businessman Jack Roeser.

Like Rostenkowski, another congressional veteran, Rep. Philip M. Crane (Ill.), the second-ranking Republican on the Ways and Means Committee, withstood a strong challenge from Peter Fitzgerald, a wealthy state senator who spent hundreds of thousands of dollars for television commercials during the campaign. With 97 percent of precincts reporting, Crane had 40 percent of the vote to Fitzgerald's 33 percent.

In other congressional races, freshman Rep. Luis V. Gutierrez (D-Ill.) easily turned back a challenge from a longtime political rival, Juan Soliz, and Rep. John Edward Porter (R-Ill.) won a rematch over his 1992 primary opponent, Kathleen Sullivan, an ally of conservative activist Phyllis Schlafly.

The most surprising aspect of the primary results was the strong showing by Rostenkowski in what was widely regarded as the most severe test of his 35-year congressional career.

"We really cleaned his clock," said one elated Rostenkowski operative who predicted that the 66-year-old incumbent would get more than 40 percent of the vote even in Cullerton's home ward.

Rostenkowski conducted a lavishly financed campaign and enjoyed the strong support of powerful national and local Democratic leaders, including Clinton. He also benefited from several late campaign missteps by Cullerton, 45, a veteran state legislator and member of a longtime Chicago political family.

But the key to his strength may have been the old-fashioned mobilization of organization support that enlisted dozens of ethnic, religious, labor and other community leaders in the Rostenkowski cause.

In the campaign's final hours, Rostenkowski began airing negative television commercials attacking Cullerton's record on crime, the issue the challenger made the centerpiece of his campaign. Rostenkowski also continued to stress his twin themes: the key role he hopes to play in steering Clinton's health care and other initiatives through Congress, and his ability to win major federal projects for Chicago.

To underscore the latter point, on Monday Rostenkowski announced a $2 million surplus Army helicopter was being given to the Chicago Fire Department to replace two helicopters lost in accidents last year."

Meanwhile, in Michigan, voters decided to raise the sales tax from 4 percent to 6 percent to generate $10.2 billion for public schools, rather than raise income taxes.

Special correspondent Megan Garvey contributed to this report.