PORTLAND, ORE., NOV. 2 -- He is one of the last of his kind, a well-mannered, silver-haired gentleman who always ran positive commercials, forged lifetime friendships with his defeated opponents and after four decades in public office thought it would always be that way.

Then, after a sudden barrage of assaults this fall, Sen. Mark O. Hatfield (R-Ore.) learned that modern-day politics could hurt even him. Democratic challenger Harry Lonsdale evened the race in the polls and "I had to do something about it," said Hatfield, graphically swinging his clenched fist a few inches past an interviewer's jaw.

Today, in a full page advertisement in the Oregonian and a biting television commercial, Hatfield took another step into the arena of personal attack, summoning a bogeyman most Oregonians thought had passed on to another world.

In the new commercial, the gnarled face of Wasco County Judge William Hulse appears on the screen to say: "Six years ago I was poisoned by the followers of the Bhagwan. A week later Harry Lonsdale wrote to the attorney general asking him to disregard the law and go easy on the Rajneeshees."

Hatfield's ad in the Oregonian reprinted that letter and another from Lonsdale, a Bend businessman of wide-ranging intellectual interests, on the same day the newspaper's front page reported a new indictment of seven followers of the late Indian guru Bhagwan Shree Rajneesh for plotting to murder U.S. Attorney Charles H. Turner in 1985 as investigators were closing in on the Bhagwan's commune near Antelope, Ore.

"I conclude that Rajneeshpuram just may be the happiest town in America," Lonsdale said in the Aug. 23, 1984, letter to state Attorney General Dave Frohnmayer. "They must be doing something right!" In a November 1985 letter to the Bulletin in Bend, a few months before the Bhagwan's chief lieutenant was convicted of electronic eavesdropping, arson and mass poisoning, Lonsdale said "the harassment and abuse heaped on this gentleman is something that all of us, as freedom-loving Americans, can be ashamed of."

Lonsdale appeared at a Hatfield news conference today on the Bhagwan affair to demand a debate, but Hatfield ignored him.

Lonsdale is already broadcasting a commercial calling the Hatfield charges "hypocritical and desperate" and quoting a 1983 Hatfield letter defending the right of Bagwan followers "to practice their faith unencumbered by government intrusions." But the fierce Hatfield counterattack appears to have halted Lonsdale's rise in the polls, reestablishing for Hatfield a small but apparently growing lead.

An Oregonian poll of 600 registered voters released Thursday showed Hatfield leading 50 to 45 percent, a slight change from his 49 to 43 percent lead in September but still far narrower than the 63 to 27 percent lead he enjoyed in August. The disappearance of that huge early lead was a sign of the damage done by a series of commercials questioning Hatfield's campaign funds from special interests, his handling of toxic waste sites and his commitment to Oregon after 24 years in Washington.

In one Lonsdale commercial, an exasperated motorist filling his tank sees the meter climb into the millions of gallons, the alleged equivalent cost of official Hatfield trips abroad. "We want to look to the future, not the past," Lonsdale says in a radio ad that ends with his campaign slogan: "Stand up for a new approach and a senator who will fight for the rest of us."

At a ceremony opening a Portland freeway interchange Thursday, Hatfield gave a demonstration of the old Oregon politics, friendly, full of humor and relentlessly bipartisan. Gov. Neil Goldschmidt, a Democrat not seeking reelection, led Hatfield around the refreshment tent in a joking search for voters. Goldschmidt has declined to endorse Lonsdale for the Senate, while strongly supporting the Democratic gubernatorial candidate, Secretary of State Barbara Roberts, who holds a 6-point lead in the polls over Attorney General Frohnmayer (R).

Goldschmidt has not endorsed Hatfield, but he will praise the Republican senator's record at the slightest urging and a close aide to the governor is working for Hatfield's campaign. "Here in Oregon," Hatfield said, offering a friendly lecture on politics in a small state, "the Rs and the Ds have always played the game pretty hard, but after the election we're still friends."

Lonsdale campaign manager Karen Olick, a veteran of elections in many larger states, suggested Oregon voters may have become impatient with such chumminess when it fills Hatfield's campaign chest with huge sums from political action committees (PACs). "People have decided they want a change," she said.

Through late October Hatfield had raised $1.3 million, much of it from PACs, while Lonsdale, who has refused PAC money, had $1.2 million, $729,000 in his own money. As useful to Hatfield as the money has been a surge of endorsements from most of the state's major newspapers and even from the counterculture Willamette Week, which embraced Hatfield's effectiveness in Washington even though "on some issues we would almost be willing to endorse Saddam Hussein over Hatfield."

But having stepped into the modern world of political attack ads, Hatfield may never be able to step out, and it remains to be seen whether he can win a race without his customary aura of righteousness. "If he is truly a statesman," Oregonian columnist Steve Duin asked, "why does he seem to be enjoying this slop?"