A new poll has Mitt Romney overtaking Rick Santorum in Pennsylvania, the state where the former senator has bet his entire campaign.

According to a new Public Policy Polling survey, Romney has opened a five-point lead over Santorum. That represents a dramatic reversal from a month ago, with Romney climbing 17 points in the polls as Santorum dropped by six in his own home state. Romney has narrowed Santorum's lead among voters who typically support the former Pennsylvania senator, such as more conservative and Tea Party-affiliated voters.

Losing the Pennsylvania primary could deal a decisive blow to Santorum's presidential aspirations. He rose to prominence in the Republican party while representing Pennsylvania, before voters ousted him by a 18-point margin in 2006. A defeat by Romney could conjure memories of that embarrassing loss.

The Public Policy Polling analysis also provides more evidence of Republican voters coalescing behind Romney's candidacy. The former Massachusetts governor won Tuesday's primary in Wisconsin -- like Pennsylvania, a relatively moderate state that will be heavily contested in the general election -- while making significant inroads among the lower-income, less-educated and more conservative voters that Santorum had carried in previous primaries.

Santorum brushed off his loss in Wisconsin, telling voters that there are plenty of primaries remaining. He also predicted a strong showing in Pennsylvania, where 72 delegates are at stake.

Half the delegates in this process have been selected, and who's ready to charge out of the locker room in Pennsylvania for a strong second half? Santorum asked supporters.

But as the calls from the party establishment  for Santorum to exit the race grow louder, Santorum has acknowledged that winning Pennsylvania is vital to his nomination hopes.

We have to win here, and we plan on winning here, Santorum said to supporters at a campaign stop at Pennsylvania diner, according to CNN. As I said last night, the people of Pennsylvania know me. All of the negative attacks are, I think, going to fall on a lot of deaf ears here. We've got a strong base of support here. And we're going to work very, very hard.

Santorum is continuing to draw a contrast with Romney by portraying his rival as out of touch with everyday voters.

You're looking at someone who, you know, knows this area - knows Pennsylvania better than, certainly anybody in this race, Santorum said, emphasizing that he grew up in a blue-collar, working class town in Butler, Pennsylvania.