PRESIDENT BUSH and his Republican Party have won a remarkable electoral victory. Elected in 2000 without a popular majority, Mr. Bush at times seemed in danger of following his father as a one-term president. He presided over a recession and launched a war in Iraq that has proved far more traumatic and costly than he predicted. Yet yesterday afternoon Mr. Bush accepted the gracious concession of his Democratic opponent, Sen. John F. Kerry, having won the first outright popular majority of any president since 1988. Mr. Bush hardly managed a landslide; he polled 51 percent of the vote and barely eked out an electoral college majority. But he will govern with the help of expanded conservative majorities in the House and Senate -- and with no question as to his legitimacy.

There will be speculation about whether Mr. Bush in his second term will "play to the base" or "move to the center." To some degree we think this is a false choice. Mr. Bush laid out a clear agenda during his campaign. He told voters that he wants to reform the tax code and Social Security, as he told them that he remains committed to victory in Iraq. It would be odd if he did not now do everything within his power to realize his goals.

But Mr. Bush was right yesterday to acknowledge that he needs broad support from all Americans. In his classy concession speech, Mr. Kerry pledged to "do my part to try to bridge the partisan divide," and we hope other Democrats follow his lead. But with Republicans controlling the entire federal government, a special obligation falls to them. That obligation can be met without sacrificing basic principles: by including Democrats in the legislative process; by nominating Supreme Court justices acceptable to reasonable members of both parties; by differing without demonizing. "A new term is a new opportunity to reach out to the whole nation," Mr. Bush said; we hope he follows through.

We would have liked to hear Mr. Bush reach out beyond the nation, too. He faces not only a divided country but a world in which many leaders, and much of the populations of other democracies, were rooting for his defeat. A new term offers an opportunity for him to show allies that he is willing to take their views into account on issues such as climate change and controlling the spread of nuclear weapons. Here, too, deference does not equal subservience; a tone of respect for world opinion could help Mr. Bush further his ambitious goals in the Middle East and beyond. And it is not too late to hold accountable the senior officials who abandoned the Geneva Conventions and precipitated the damaging prison-abuse scandal of the first term.

Even with his 3.5 million-vote margin and his friendly congressional majorities, Mr. Bush may need all the help he can get. "Because we have done the hard work," he said yesterday, "we are entering a season of hope." He's entitled to dream on this day of celebration, but plenty of hard work lies ahead. The nation is living beyond its means in ways that could spell trouble for the dollar and for Americans' standards of living. In Mr. Bush's first term the government began racking up huge budget deficits , and the president has offered no plan to get them under control. He talked during the campaign as though Social Security could be transformed cost-free. In fact, its looming shortfall, like Medicare's, must be faced, and Mr. Bush's style of reform would make doing so far more expensive, at least in the coming decade.

Most of all, Mr. Bush faces challenges abroad. The terrorist threat remains the first priority. A genocide in Darfur has been honestly labeled but inadequately dealt with. A rising China, and its relations with democratic Taiwan, were barely mentioned during the campaign. Afghanistan, having successfully conducted its first election, needs continuing help and attention.

And then there is Iraq, and the continuing terrible violence from insurgents there. When we endorsed Mr. Kerry, our greatest trepidations centered on the level of his dedication to success. Mr. Bush leaves little doubt on that score, but it was his record of blithe indifference to the magnitude of the challenge that helped lead us to vote for his opponent. Now we hope the president will assemble a team that matches in competence and hard-headedness his own determination.