Mitt Romney continues to struggle in a basic test of popularity among independents, scoring far below recent Republican presidential nominees and setting up an obvious challenge for him even if he fares well on Super Tuesday and moves further along the path to the top of the party’s ticket.

Nearly half of all political  independents questioned in a new Washington Post-ABC News poll express unfavorable views of the former Massachusetts governor. At 48 percent unfavorable among this key bloc, Romney’s numbers are among the worst he’s received; far fewer, 32 percent, view him favorably.

Of the four remaining GOP contenders, Rep. Ron Paul (Tex.) draws the most even ratings from independents, winning a split verdict of 38 percent favorable and 35 percent unfavorable. His challenges are within the party base; he has yet to win a primary contest.

Among independents, negative ratings of former Pennsylvania senator Rick Santorum outnumber positive ones by 42 to 30 percent. Newt Gingrich gets decidedly bad reviews here as well: 58 percent unfavorable and 21 percent favorable.

With a 35 percent favorable rating among all Americans, Romney -- the leader in delegates -- is well off the mark set by previous GOP front-runners at similar times in the presidential election cycle. Eventual Republican nominees John McCain in 2008, George W. Bush in 2000, Bob Dole in 1996, and George H.W. Bush 1988 were all rated more highly by the general population.

Romney’s numbers among independents are also worse than other Republican front-runners. At this time four years ago, more than half of independents expressed favorable views toward McCain; nearly that many independents had favorable views of Dole and George H.W. Bush at this point during their runs.

Among Democrats, Romney’s ratings continue to hover just below 20 percent favorable, at least 10 points lower than other GOP nominees in previous cycles.

The Washington Post (Jon Cohen/The Washington Post)

Still, as far as the nomination goes, only Santorum rivals Romney among Republicans. Heading into Tuesday’s votes, 60 percent of Republicans view Romney favorably. Santorum checks in at 58 percent among the party base. For both Gingrich, the former House speaker, and Paul, about as many Republicans see them unfavorably as favorably.

And in a bit of a rebound, 67 percent of conservative Republicans rate Romney favorably, an 11-point bump up following some slippage in the crucial group.

Santorum continues to excel among these conservative Republicans (68 percent favorable; 21 percent unfavorable), but overall, his numbers have turned decidedly negative for the first time this year. Among all Americans, 32 percent hold favorable views, and 40 percent unfavorable ones. That’s a nine-point jump in negatives from just three weeks ago.

Paul and Gingrich also hit new highs on personal negatives for the cycle, amplifying another new finding that Obama may be the main beneficiary of the ongoing Republican nomination battle.

The poll was conducted Feb. 29 to March 4, among a random national sample of 1,014 randomly selected adults. The results from the full poll have a margin of sampling error of plus or minus 3.5 percentage points.