WASHINGTON -- Two new polls in Wisconsin show Mitt Romney leading Rick Santorum by a comfortable margin with just four days remaining before Tuesday's Republican primary. The results suggest that time is running out for Santorum in a state some dub as "win or go home" or a "last chance" for the former Pennsylvania Senator.

The most recent survey, released on Friday by NBC and Marist College and conducted March 26-27, shows former Massachusetts Gov. Romney with a seven-percentage-point lead over Santorum (40 percent to 33 percent), with Rep. Ron Paul (R-Texas) at 11 percent and former House Speaker Newt Gingrich (R-Ga.), with 8 percent, running far behind.

The NBC/Marist results are virtually identical to a survey fielded earlier in the week (March 22-25) by the Marquette University Law School that found Romney leading by eight points (39 to 31 percent), followed by Paul (11 percent) and Gingrich (5 percent).

2012-03-30-Blumenthal-WIpolls.png

The two new polls were conducted using live interviewers and called samples of both landline and mobile telephone numbers.

An automated, recorded-voice Rasmussen Reports survey conducted last week had Romney leading by an even larger margin (46 to 33 percent), but that survey was fielded in the midst of favorable news coverage following Romney's double-digit victory in the Illinois primary.

The HuffPost Pollster Wisconsin chart, shown below, plots the results of all of the surveys fielded in Wisconsin in the last five months. Romney's apparent lead in Wisconsin represents a reversal from two surveys conducted in February by the Marquette Law School and Democratic firm Public Policy Polling (PPP) that both showed Santorum leading.

The turn-around is not surprising given both increased support for Romney seen in national polls of Republicans since mid-February, and the now-usual disparity in advertising spending in Wisconsin between the Romney and Santorum campaigns and their allied super PACs. As the Huffington Post's Paul Blumenthal reports, anti-Santorum super-PAC ad spending in Wisconsin has exceeded anti-Romney super-PAC spending by better than three-to-one.

Beyond its symbolic value, a victory in Wisconsin could also provide Romney with a significant boost in pledged delegates. Wisconsin will allocate its 42 delegates on the basis of next Tuesday's vote. The statewide winner will receive all of the 18 at-large delegates, while 24 delegates elected in Wisconsin's eight congressional districts will be allocated on a winner-take-all basis within each district.

The NBC/Marist poll shows Romney leading by double-digit margins in Milwaukee and the counties in the Milwaukee metro area, so Romney would be the heavy favorite to the three metro Milwaukee districts. The poll shows either a closer contest or a slight Santorum lead in the other more rural portions of the state, but Romney could win between 27 and 33 of Wisconsin's 42 delegates by carrying the state and some or all of the districts in Southeast.

NBC's First Read reported Thursday that, according to its calculations, "Santorum can't stop [Romney] from getting to the magic number of 1,114 delegates," should Romney win in Wisconsin.

More polls are likely to be released over the weekend and on Monday, and those should further clarify the current standings, but for now, Rick Santorum's hope for a reversal of fortune in Wisconsin appears unlikely.

Related on HuffPost: