The Republican race has changed, and changed in a profound way.
With Rick Santorum's three victories Tuesday in Missouri, Minnesota and Colorado, the whole nature of the 2012 Republican presidential campaign has changed.
First, the air of inevitability that Romney had after the Florida is gone.
The fact that the Massachusetts governor was unable to win any of the three states, and lost Minnesota and Missouri by wide margins suggests very clearly that this could well be a long campaign-- one that could well go to the convention.
In both Colorado and Minnesota, Governor Romney had won by large margins in 2008, and even going into Tuesday's contest, the former Massachusetts Governor was expected to win the Colorado caucus -- at least comfortably.
Governor Romney has had trouble winning a majority of the vote anywhere, doing it just once in Nevada, and former Senator Santorum has now actually won more contests than Governor Romney.
To be sure, no delegates were at stake in any of the contests in Colorado or Minnesota, and the Missouri primary also did not give Santorum any additional support in the formal nominating process.
Still, there are a number of implications going forward.
First, Governor Romney can't do what he did in Florida, which is to turn his attention almost exclusively to President Obama. He must continue to focus on his Republican opponents, and use the great advantage he has enjoyed-- substantial financial resources-- to attack his opponents. Such a strategy works, as we saw in Florida, but it could well drive up Governor Romney's negatives, not only with Republicans, but with key critical swing voters to win independents.
Second, Governor Romney has to stay on the right. The vast majority of the support Santorum got was from social and economic conservatives on Tuesday, and Governor Romney has to move right to hold that support.
To be sure, Governor Romney has a resource and organizational advantage going forward. He should do well in Arizona and Michigan on February 28th, and he will need, in the 10 states that conduct primaries and caucuses on Super Tuesday on September 10th, to win in at least half or close to half the contest being held that day.
Super Tuesday is also the last stand of Newt Gingrich, who will have to do well through the South to remain viable. The recent Rasmussen polling shows Gingrich in second place, but ominously for Romney, his lead in that survey and the Reuters polling shows the former Massachusetts Governor's lead having been cut in half in the past few days.
So the Republican contest is, once again, wide open. Romney's vulnerability on the right has become clear. Santorum's strength with social conservatives reinforced.
The big winner, once again, is President Obama.
Douglas E. Schoen is a political strategist and Fox News contributor. Schoen, who served as a pollster for President Bill Clinton, is author of several books including the forthcoming "Hopelessly Divided: The New Crisis in American Politics and What It Means for 2012 and Beyond" (Rowman and Littlefield). Follow him on Twitter @DouglasESchoen.