PHOENIX — Hillary Clinton is maintaining her lead among Democrats in Arizona despite the endorsement of her leading foe by Gov. Janet Napolitano.

 A new survey of 366 likely voters shows the senator from New York is the choice of 30 percent of those questioned. By contrast, Barack Obama is the pick of 17 percent, with John Edwards far back at 5 percent.

 And when pollster Bruce Merrill factors in those who are leaning toward one of the candidates, Clinton picks up 45 percent of the vote against Obama’s 24 percent.

 Both figures have a 5.1 percentage point margin of error. Merrill said that lead is about the same as it was in October — and the same as it was before the governor’s Jan. 11 endorsement of the Illinois senator. But Merrill, who conducted the survey for KAET-TV, the Phoenix PBS affiliate, after that endorsement, said the failure of Napolitano to move the numbers is no surprise. “We have kind of a value that says ‘We don’t like having other people tell us what to do anyway,’ ‘’ Merrill said. He said that’s why numerous studies have shown that endorsements — even by a governor that many Democrats admire — only help in the margins. “Obama would prefer to have her endorsement rather than not having it,’’ Merrill said. “But unless the race were down to  few hundred people or something, there’s just little evidence that political endorsements are a big factor.’’

 Merrill said his survey reflects was designed mainly to test the views of the perhaps one third of registered Democrats who are likely to go to the polls on Feb. 5. He said it’s not surprising these “high efficacy’’ voters are Clinton supporters, as they tend to be people who are older and “have worked in the party for years.’’

 By contrast, Merrill said, Obama’s support comes more from “non-traditional voters, younger voters, alienated voters.’’

 Merrill said the poll does suggest that Obama is making a mistake with his new tactic of attacking former President Bill Clinton.

 He pointed out that 12 percent of those who said they support Hillary Clinton said their prime reason is because they like her husband or believe that he would be a help to her. And another 9 percent said they will vote for her because the nation needs a woman to be president.

 On the Republican side, Merrill found John McCain maintaining a wide lead. He tallied the backing of 28 percent of likely voters — 41 percent if you add in those who are leaning in his direction. Former Massachusetts Gov. Mitt Romney is supported by 10 percent of those asked; counting those leaning toward Romney his backing rises to 18 percent.

 Mike Huckabee, Rudy Giuliani and Fred Thompson — who dropped out Tuesday — were all in single digits. That survey of 375 Republicans has a 5 percentage point margin of error.