The first week of the new year brought a sharper focus and clear movement to the presidential campaigns of Republican George W. Bush and Democrat Al Gore. Bush dived right. Gore lurched left, with a misstep.

Bush and Gore once had the general election--and each other--squarely in their sights, appealing to swing voters and hugging the center to prevent the other from occupying that ground.

But competitive nomination fights demand a different approach. "Both started out running general election campaigns that ultimately created a vacuum in their own parties," said Democratic pollster Geoff Garin. "Gore experienced the danger of that earlier than Bush did, but ultimately they had to retrench and run much more traditional nominating races."

Last week above all proved that. From gays in the military to religion in the Oval Office, all the Democratic and Republican candidates were playing to their party bases and not the electorate at large in the most intensive week of the campaign to date, a week that included four debates, two prominent endorsements, several theme-setting speeches and a flurry of new television ads.

The candidates crisscrossed Iowa and New Hampshire, with a GOP detour to South Carolina for a Friday-night debate, mindful of the clock ticking down toward the first two events of the nominating season, the Jan. 24 precinct caucuses in Iowa and the Feb. 1 primary in New Hampshire.

There is another parallel between Bush and Gore that became clearer last week. Aides to each believe that, if their candidates can win in both Iowa and especially in New Hampshire, they will make it virtually impossible for their principal rivals, Bill Bradley and John McCain, to prevent them from winning the nominations.

For the vice president, the week began with a long-sought endorsement from Massachusetts Sen. Edward M. Kennedy (D) and ended with an embarrassing rollback over whether he would make allowing gays to serve openly in the military a litmus test for appointments to his Joint Chiefs of Staff.

His stumble on the litmus test on gays brought a clear moment of discomfort for the campaign but was a reminder of the kind of voters he and other candidates have on their minds this month.

The week also brought a clearer focus to the competition between the two Democrats--and the themes that will dominate the next three weeks of campaigning.

As framed by Bradley, it is the difference between a bold leader prepared to take on big issues vs. a politician trapped in an incremental, Beltway mentality. As framed by Gore, it is a battle between an experienced politician ready to tackle a host of problems vs. a dreamer who can't deliver--or as Garin described Gore's argument: "a real-world go-to guy versus a seminarian."

Throughout the week, much of what Gore did and said appeared aimed at rallying the support of the party faithful by attempting to prove to them that he is a more reliable Democrat than the former New Jersey senator--and the Democrat best equipped to carry forward President Clinton's policies.

Gore kept up the pressure against Bradley's health care plan, but with increased focus on its potential effect on two programs dear to the Democratic Party: Medicare and Medicaid. Today in their debate, Bradley dismissed Gore's attacks as "a scare tactic."

Gore also appeared more comfortable embracing the Clinton presidency, mindful that whatever Democrats may think about Clinton's behavior, they support his record on the economy and other issues.

In the Wednesday night debate at the University of New Hampshire, Gore vigorously defended his support for Clinton during last year's impeachment battle, reminding Democrats that he was fighting to block what he called a partisan effort by Republicans to end the Clinton presidency.

And then there was the unveiling of the Kennedy endorsement, first in Boston, next in New Hampshire and finally across Iowa on Friday. Kennedy, the old liberal lion, was in full throat in behalf of the vice president, with a vintage performance that was designed to energize the Gore troops--and erode Bradley's support among liberal Democrats.

Bradley dismissed the Kennedy endorsement as another sign of the "entrenched power" working to make Gore the Democratic nominee. Inside the Gore campaign, the first returns on the endorsement were positive. "We clearly got a bump up from Kennedy's endorsement," one top adviser said.

On the ground, Bradley's campaign demonstrated energy in both Iowa and New Hampshire. But the candidate appeared at times last week to be struggling to strike the right balance in how to conduct his campaign. Should he continue to war with Gore over health care, guns, education and agriculture or decry "the meanness and pettiness" of politics and rise above the rat-a-tat of the debate?

"We're going to pick the times when the vice president has crossed the line" to engage, a Bradley adviser said. "But for Bill Bradley, this election is about articulating the purpose of being president--what you get done as opposed to listing a huge number of issues, a laundry list."

Bradley tried to find that balance toward the end of the debate on Wednesday night when he accused Gore of living in a "Washington bunker." He charged that political survival of the Clinton-Gore administration had taken precedence over tackling big problems. "But the reality is, the Democratic Party shouldn't be in the Washington bunker with you," Bradley said. "The Democratic Party should be thinking big things with big ambitions."

Whether Bradley can seize enough of the Democratic heart and soul with that kind of appeal to defeat the vice president is the test of the next few weeks. At this point neither campaign sounds overly confident. "The truth is, it's a tough battle for both of us," a Gore adviser said.

Bush's effort to appeal to the right was equally clear. After an autumn devoted to his version of political triangulation--pushing off against his party in Congress to demonstrate that he is a different kind of Republican--he hit the trail last week determined to prove that he is the true conservative.

On tax cuts and campaign finance reform, he sought to link McCain with the Democrats, hoping that voters in the GOP primaries will think twice about choosing McCain. The only people who have criticized his tax cut plan as too big and too tilted to the rich, Bush said, were McCain and Gore. McCain's campaign finance reform would help Democrats and "hurt Republicans and hurt the conservative cause."

Like Gore, Bush found his nomination suddenly in competition with a candidacy based as much on character as on ideas. Like Gore, Bush has responded by redoubling efforts to shield himself with issues important to the GOP base.

In a New Hampshire debate on Thursday night, he took the state's infamous anti-tax pledge a step further than ever, declaring not only that he would not raise taxes but also that he would bring about "tax cuts, so help me God." But rival Steve Forbes says in a new ad that Bush shouldn't be trusted because he broke an earlier pledge in Texas.

McCain, the anti-establishment reformer, sought to burnish his conservative credentials as well. He launched a television ad in South Carolina featuring Rep. Lindsey Graham, who touted the Arizona senator's "17-year pro-life voting record" and his support for legislation "to take pornography off the Internet."

But McCain spent much of the week trying to limit the fallout over revelations that he had intervened before the Federal Communications Commission in behalf of a campaign contributor. McCain said he had merely urged the FCC to act in a long-delayed television licensing case, but his aides worried about how much damage it would cause, and scrambled to contain the damage by releasing a stack of documents today. "We don't know whether it's a two- or three-day story or a five- or six-day story," one adviser said. "That will make a big difference."

Bush carefully avoided harsh criticism of McCain but used the issue to erode McCain's appeal as one who can shake up the Washington establishment. Bush noted that McCain was in Washington long enough to rise to chair a powerful committee and argued that he, a governor, is the true Washington outsider.

Bush, like Gore, also used an endorsement to rally members of his own party and grab the headlines for a day when he showed up in New Hampshire Tuesday morning with former rival Elizabeth Dole. Her campaign never got off the ground, but the flashing cameras from members of the audience were a reminder that she retains celebrity appeal within the party.

Gore and Bush might have preferred to run other kinds of campaigns, although it's likely that they knew January would bring a shift away from the center. Whether they and their rivals will do and say things to win their nominations that will damage their chances of winning in the fall is now a clear risk.

Gore's quick effort to restate his position on a gay litmus test for the Joint Chiefs showed the danger of trying too hard to appeal to his party's core constituencies. But failing to do so could be even more costly.

CAPTION: Presidential candidate George W. Bush and his wife, Laura, share a laugh during a Friday stop in Rochester, N.H. Bush was determined last week to prove he was the true conservative as he sought to rally the GOP faithful.