Bolstered by the twin engines of electability and perceived inevitability, Mitt Romney's on a roll, advancing in the latest ABC News/Washington Post poll to a 2-to-1 lead over his closest competitor in support for the Republican presidential nomination.

Coming off his eight-vote victory in Iowa and strong showing in New Hampshire, a vast 72 percent of Republicans and Republican-leaning independents now expect Romney to be their nominee - up by 32 points from mid-December. Fifty-seven percent, moreover, call him their best chance to win in November, nearly triple the September level, with a 19-point jump in the last month alone.

Given these advantages, Romney now holds 35 percent support for the nomination, with his closest competitors bunched in the teens - 17 percent for Newt Gingrich, the latest in a string of contenders to see his support collapse; a steady 16 percent for Ron Paul; and 13 percent for Rick Santorum, who is up 10 points since his strong second in Iowa, but still far behind Romney nationally.

Romney's previous high was 30 percent in ABC/Post polls last month and in July. His support has firmed as well as grown, with 43 percent of his backers saying they're definitely for him, with no chance they'll change their minds - up steadily from 28 percent in November.

While that leaves enough flexibility for the race to shift, Romney has gained ground as the consensus candidate. This poll, produced for ABC by Langer Research Associates, finds Romney leading as second choice among leaned Republicans who currently favor others. And just 8 percent say they definitely would not back him for the nomination, putting him last on the list of unacceptable candidates. About a quarter, by contrast, rule out Paul and Gingrich alike.

Among Romney's other strong cards, four in 10 leaned Republicans say he has the best temperament and personality for the presidency; that falls to the low teens for Gingrich and Santorum and to the single digits for Paul and Rick Perry. Romney also leads in trust to handle four out of five issues tested (he's numerically behind Gingrich only on "international affairs.") He's gained eight points since December in trust to handle the deficit and leads broadly on the economy. Even on handling social issues, Romney leads Gingrich and Santorum, by 10 and 11 points, respectively.

Jon Huntsman's departure is not a significant factor in Romney's advance. Huntsman had just 3 percent support in this poll, completed Sunday, a day before he quit the race. Allocating his backers' second choice gives one point to Romney, one to Gingrich, with the rest scattered.

RISKS - Romney does face some challenges. Compared with electability and temperament, he's more weakly rated on having the best experience, best representing core Republican values, saying what he believes, being honest and trustworthy, and understanding the problems of "people like you." He doesn't clearly trail on any of these, but neither does he clearly lead; and these attribute ratings generally are flat for Romney from last month, while Santorum has gained as many as 9 points, albeit just to the teens.

Romney's chief vulnerability would be for some of the groups in which he's struggled - very conservative Republicans, evangelical Christians and strong supporters of the Tea Party movement - to coalesce around an alternative. So far, though, no dice. Consider:

•  Romney has 34 percent support among evangelical white Protestants, up from 20 percent in December. He's now numerically leading (albeit not statistically significantly) in this core Republican group.
• He's got 29 percent support among very conservative Republicans and Republican-leaning independents, enough for first place, at least numerically, in this group. And he's up by a broad 18 points among moderates from last month, to 48 percent support.
• Romney gets 28 percent among "very" strong supporters of the Tea Party movement, about even with Gingrich's 27 percent. The tea party, as an aside, has slipped to its lowest support on record, 40 percent among Americans overall.

Romney's managing other risks. There's been a 9-point drop since last month in the number of potential Republican voters who see his record on health care as a major reason to oppose him. And he appears little damaged by charges that he chain-sawed jobs while running the corporate takeover firm Bain Capital. Fifty-one percent of leaned Republicans have a favorable opinion of his business experience (about the same as last month), and by 50-28 percent more think he chiefly created jobs at Bain than cut them.

The jobs issue, though, is not fully resolved. His unfavorable rating on his business experience is up by 9 points, to 29 percent. And a substantial number of leaned Republicans, 23 percent, are unsure whether he chiefly created or cut jobs, which is an issue that matters in his support. Among those who see him as a job creator, Romney wins 50 percent support. That falls to 25 percent among those who aren't sure about his record on jobs, as well as 18 percent among those who think he's mainly cut them.

GENERAL - Questions about Romney's background at Bain Capital may show bigger teeth in a general election campaign. By 55-35 percent, more Americans express concern about the economic system favoring the wealthy than about overregulation fettering free enterprise, an issue that will likely be a sharp point of contention between Barack Obama and whichever Republican he faces.

There are major partisan divisions on the question: Seventy-nine percent of Democrats see unfairness in the economic system as the bigger problem; just 30 percent of Republicans agree - but 52 percent of independents side with the Democrats. So do significantly more young adults, women, racial minorities, less well-off and the least-educated Americans, compared with their counterparts.

Unsurprisingly given these groups, those who see economic unfairness as the bigger problem disproportionately trust Obama over the eventual Republican nominee to address it, 64-28 percent. Those who see overregulation as the greater concern prefer the GOP approach, 74-21 percent. Given the greater concern over economic fairness, there's potential advantage here for Obama.

As things stand, the potential matchup between Obama and Romney remains very close. Among all adults, 47 percent currently prefer Romney, 46 percent, Obama. By contrast, Obama leads Paul, Santorum and Gingrich by 8-, 13- and 15-point margins, respectively.

THE OPPOSITION - To get to Obama, one of Romney's opponents first must overcome Romney - and as noted, that's not getting any easier. While Romney's strengths are one problem they all face, each also has significant weaknesses of his own. Among them:

• Gingrich, in addition to seeing his support shrink by 13 points from last month, takes a hit for his work as a consultant for companies with an interest in federal policy making. Last month more Republicans and Republican leaning-independents saw this unfavorably than favorably, by 44-33 percent. Now that's widened to a 51-29 percent negative split.
• Paul, who finished third in Iowa and second in New Hampshire, continues to alienate many of his non-supporters. Within his own party, 50 percent of leaned Republicans think that if elected Paul would pursue policies that most people in this country would find unacceptable. On one specific issue, 49 percent call his opposition to U.S. military interventions "a major reason" to oppose his candidacy, twice as many as see it as a major reason to support him.
• Santorum, for his part, draws a 65 percent unfavorable response from potential Republican voters for his position that abortion should be illegal in all cases, including cases of rape, incest or mortal danger to the mother. And by more than 2-1, 31-14 percent, leaned Republicans see his support of earmarks while a U.S. senator as a major reason to oppose his candidacy.

Leaned Republicans' satisfaction with the candidates, at 61 percent, is not high. But more are learning to like Romney, not least given his perceived electability. Changeability is such that one of his opponents could catch him; overall, 60 percent of potential GOP voters say they still may change their minds. But as Romney pushes on to South Carolina and Florida beyond, his opponents' time is running short.

METHODOLOGY - This ABC News/Washington Post poll was conducted by telephone Jan. 12-15, 2012, among a random national sample of 1,000 adults, including landline and cell-phone-only respondents. Results have a margin of sampling error of 3.5 points for the full sample. The survey was produced for ABC News by Langer Research Associates of New York, N.Y., with sampling, data collection and tabulation by Abt-SRBI of New York, N.Y.