WASHINGTON — Just a few weeks ago, advisers to Mitt Romney spoke about a steady, gradual climb from obscurity to the 2008 Republican presidential nomination.

Now, Romney has rocketed from behind and is leading the race or is neck and neck for the lead in the pivotal states of Iowa and New Hampshire.

The road to next January's voting still is marked by numerous potholes, including persistent charges that he's a flip-flopper without conviction, a Mormon faith still unfamiliar and perhaps suspect to some voters as well as potential new competition from former House Speaker Newt Gingrich and former Sen. Fred Thompson.

Also, his rapid rise may say as much about the fickleness of Republicans this early in the campaign as it does about the former Massachusetts governor.

But for now at least, Romney enters the summer astride the top tier and within reach of being able to claim that he's the front-runner for the nomination.

"He clearly has the three M's: media, money and momentum," independent pollster John Zogby said.

Romney led the field in fund raising in the first three months of this year. Yet until now, he trailed in popularity well behind Rudy Giuliani and Arizona Sen. John McCain in most polls, either nationally or in early voting states such as Iowa, New Hampshire or South Carolina.

However, a poll in Iowa by The Des Moines Register last week found Romney leaping ahead with the support of 30 percent of likely attendees at January's precinct caucuses, well ahead of McCain's 18 percent and Giuliani's 17 percent.

In another new Iowa survey by the Republican public relations firm Strategic Vision, Romney led with 20 percent, up sharply from 8 percent the month before. He was followed by Giuliani with 18 percent and McCain with 16 percent.

(A third poll showed McCain with 18 percent, Giuliani with 17 percent and Romney with 16 percent.)

Romney surged in New Hampshire as well. A new Zogby poll there found he had the support of 35 percent of likely primary voters, up from 25 percent the month before. That was well ahead of Giuliani and McCain, each with 19 percent.

Analysts and insiders pointed to three reasons for the Romney rise:

• Good reviews from party members and pundits for his performance in the party's first debate, May 3 in California.

• Unusually early television advertising in Iowa and New Hampshire. Romney has been advertising there for weeks, boasting about his record as a business executive and governor. A new ad Thursday bragged that he cut spending and taxes as governor and "enforced immigration laws, stood up for traditional marriage and the sanctity of human life."