A new WMUR/CNN poll released this afternoon shows that among likely primary voters, frontrunner Mitt Romney has dropped 10 percentage points, from 33 percent to 23 percent, since July. The survey shows his rivals gaining ground, with Rudy Giuliani creeping up to 22 percent, from 18 percent in July, and John McCain rising to 17 percent from 12 percent. Fred Thompson, meanwhile, who officially joined the race earlier this month, barely moved: The poll shows him at 12 percent, compared with 13 percent in July. The sampling error was plus or minus 5.4 percentage points. Sixty-six percent of respondents said they were still trying to decide whom to vote for. Only 13 percent said they had definitely decided. "There is absolutely no clear frontrunner in this race," Andrew Smith, director of the UNH Survey Center, which conducted the poll, told WMUR. Giuliani has the best favorability rating, with 71 percent viewing him favorably and 22 percent viewing him unfavorably. They also rate Giuliani as the most likeable candidate and the one with the best chance of defeating the Democratic nominee. But Romney's attempts to portray himself as the candidate who represents change in Washington -- the main emphasis of his recent TV ads and a key speech in Michigan last weekend -- appears to sinking in. Twenty-five percent said Romney was the candidate who could "bring needed change," compared with 18 percent for Giuliani and 13 percent for McCain. McCain got the highest ratings for having the "right experience" to be president, followed by Romney and then Giuliani.