The Wisconsin primary is this Tuesday, and it may signal the end for the other candidates if Romney gets a win.
As of right now, that very outcome is looking very likely. Romney is currently picked to win the Wisconsin primary. However, Santorum is showing no signs of stopping. He has reportedly said on multiple occasions that he will stay in the race until Romney grabs the delegates needed to win the nomination.
Also, there are some people out there who are not only calling for Gingrich and Paul to drop out but for Santorum to do the same as well, even though he is Romney’s closest contender.
As of right now, the only candidate that seems to be signaling that the end is near for his race to the white house is Gingrich.