McCain faces obstacles on several fronts. He would be the oldest person to start a first term as president, and three in 10 survey respondents think he is too old for the job. McCain is also in danger of overplaying the endorsement he received this week from President George W. Bush. Campaigning side by side with the unpopular president could hurt McCain's chances; the president's approval rating hovers around 30 percent. Even among Republicans, almost a third (32 percent) of survey respondents said they disapprove of the job Bush is doing. Finally, McCain's support of the Iraq War may backfire. Although a slightly greater number of voters believe that things in Iraq are getting better (29 percent) rather than worse (25 percent) that could swing quickly if U.S. casualties flare.

The rest of the poll results were mixed. They suggested that Clinton's ominous "3 a.m. phone call" ad benefited her campaign. Almost half (45 percent) of Democrats said they would trust Clinton to answer the red phone in the wee hours, while only a third felt that way about Obama. Similarly, on the issue of national security, almost half (47 percent) of the Democratic base said that they trust Clinton to protect the country; only a third feel the same about Obama.

But it's not clear how much these sentiments will matter at the ballot box: just 4 percent of Democrats overall, and 4 percent of Clinton's supporters, name terrorism as their top issue. When all voters were asked which of the three candidates they would most trust to take a 3 a.m. call, the largest number pointed to McCain (45 percent), followed by Clinton (27 percent) and Obama (18 percent). Almost a fifth of Clinton's supporters say that they would trust McCain more to take the call.

Looking ahead, 58 percent of Democratic voters, and 44 percent of Clinton backers, believe she will "go negative" if she wins her party's nomination. In contrast, only 24 percent of Obama supporters expect him to take the low road--which suggests that his backers could penalize him for playing dirty. The poll also shows that Clinton remains a divisive figure: a full 40 percent of registered voters hold an unfavorable opinion of her, compared with 35 percent for McCain and only 28 percent for Obama. On Clinton's contention that the media is harder on her, 42 percent of Democrats agree. Even among Obama supporters, a full third believe their candidate has had an easier time with journalists.

While Clinton has regained support among national Democrats, Obama maintains the lead among pledged delegates to the party's convention, with 1,366 versus Clinton's 1,227, according to the tally by NBC News. Both fall short of the 2,025 delegates required to secure the nomination. But the national sentiment in the lastest NEWSWEEK Poll could reflect shifting attitudes of voters in upcoming primaries, including the next big prize, Pennsylvania.

Should neither Clinton nor Obama secure enough delegates to win the nomination (a scenario that looks increasingly likely), 43 percent of Democrats said they would prefer that the candidate trailing in the delegate count concede the nomination, while 42 percent think superdelegates should choose the nominee. Should the ball end up in the superdelegates' court, most respondents (42 percent) think they should choose the best-qualified nominee in their judgment, while 38 percent believe they should choose the person with the popular vote lead.