Washington ? Widespread unease over the country’s direction and doubts about President Bush’s policies on Iraq and the economy helped propel Sen. John F. Kerry to a solid lead among voters nationwide, according to a new Los Angeles Times Poll.

Yet in a measure of the race’s tenuous balance, Times polling in three of the most fiercely contested states found that Bush had a clear advantage over Kerry in Missouri and was even with the presumed Democratic rival in Ohio and Wisconsin.

The survey suggested that attitudes might be coalescing for a contest that will pivot on the classic electoral question at times of discontent: Will voters see more risk in stability or change?

More than one-third of those questioned in the nationwide poll said they didn’t know enough about Kerry to decide whether he would be a better president than Bush. And when asked which candidate was more likely to flip-flop on issues, almost twice as many named Kerry as named Bush.

Yet Kerry led Bush 51 percent to 44 percent nationally in a two-way matchup, and 48 percent to 42 percent in a three-way race, with independent Ralph Nader drawing 4 percent.

Lifting Kerry is a powerful tailwind of dissatisfaction with the nation’s course and Bush’s answers for challenges at home and abroad. Nearly three-fifths said the nation was on the wrong track, the highest level a Times Poll has recorded during Bush’s presidency.

Fifty-six percent said America needed to “move in a new direction” because Bush’s policies had not improved the country. Just 39 percent said America was better off because of his agenda.

Majorities disapproved of Bush’s handling of the economy and Iraq, despite recent encouraging news on both fronts.

The survey showed that Bush still enjoyed significant political strengths, including virtually undivided support from his base and continued admiration for his handling of the struggle against terrorism. Nationally, his general approval rating was just above 50 percent.