CONCORD, N.H.-- There has been a sudden sea change in the Republican presidential campaign as the prime rivals of Senate Majority Leader Bob Dole have increased sharply both the intensity and tone of their attacks on the front-runner.
Mr. Dole has been the butt of some sniping from Sen. Phil Gramm of Texas for several months. And he has been the target for several weeks of a steady drumfire of attack television commercials financed by magazine publisher Malcolm S. "Steve" Forbes Jr.
But Mr. Gramm has added more heat to his attack by using a new television commercial borrowing footage from a spot used here by George Bush in 1988, labeling Mr. Dole "Senator Straddle" and assailing him on the tax issue that is always the most sensitive in New Hampshire primary campaigns.
Perhaps more importantly for the long run, former Gov. Lamar Alexander of Tennessee has begun to strike at the most sensitive vulnerability of the front-running Senate leader: the question of his electability and, by implication, of his age (72).
Mr. Alexander laid out his case last week in a speech to the Heritage Foundation in Washington and has now incorporated the same language into his standard speech on the stump. The Republican Party, he argues, "needs a wake-up call" lest it lose not only the presidential election but control of the House of Representatives if Mr. Dole heads the GOP ticket.
Mr. Alexander deals with the age issue only tangentially. "We must bring ourselves to say to Senator Dole, with respect, 'We appreciate your long service,' " but that he is not the right candidate this year, he told a gathering here yesterday.
The core of his argument is that Mr. Dole is too wedded to practicing conventional politics and that he lacks the vision to confront President Clinton effectively.
"It is time for a new generation of leadership," Mr. Alexander said in the Heritage speech. "It is time to move on. If the nominee is XTC unable to articulate the vision of the revolution, he will not only fail to win the White House, he could drag others to defeat with him -- putting the House and the revolution itself at risk. It is time for Republicans everywhere to stop ignoring the Dole undertow."
Mr. Gramm's spot recalling the "Senator Straddle" commercial was shown first in South Carolina late last week and given widespread news coverage here, where Republican insiders remember it as the commercial that sank Mr. Dole here eight years ago after he had defeated Mr. Bush in Iowa.
The Texas Republican uses the ad to make an essentially ideological argument that Mr. Dole is not committed enough to hard-line conservative positions, including the balanced budget, and too willing to compromise. His rival, Mr. Gramm says, "lost his nerve and caved in" when he moved to end the shutdown of the federal government. "I am not going to lose my nerve," he added.
Mr. Dole's supporters depict the attacks as the product of the frustration of the trailing candidates.
"It surprises me," Gov. Steve Merrill, a leading Dole backer here, said in an interview, "that it hasn't changed greatly over the last four weeks." One reason, Mr. Merrill suggested, may be that the saturation television advertising being run by Mr. Forbes -- he has spent more than $7 million since September -- has made it impossible for other candidates to be heard.
David Carney, Mr. Dole's chief strategist here, agrees. "I think he [Mr. Forbes] is really killing those other guys," he said. "Nobody's talking about them."
Political history lends some support for both positions. Mr. Dole's display of strength in the opinion polls week in and week out is unusual enough to persuade many professionals that his lead will be difficult to overcome.
But the doubts about Mr. Dole's electability are pervasive enough to suggest that the Senate leader is far from invulnerable when so few of the early caucus and primary voters have yet to focus on the campaign.
The operative question is how vulnerable he may be. Polls here have shown his negatives rising in an apparent response to the attacks in the Forbes commercials. This pattern has convinced Mr. Alexander and his strategists that Mr. Dole's viability for the general election can be called into question.
But recent national surveys show that Mr. Dole's standing against Mr. Clinton has improved measurably since the Republican leader took the initiative in trying to end the government shutdown -- an improvement that appears to undermine Mr. Alexander's new line of attack.