Editor's note: Ruben Navarrette Jr. is a CNN.com contributor and a nationally syndicated columnist.
San Diego , California (CNN) -- Now that Rick Santorum has scored victories in this week's Republican primary contests in Mississippi and Alabama --this after his earlier win in Tennessee and Newt Gingrich's victory in South Carolina -- it's time to confront three questions:
1. Can we in the media really keep referring to Romney as the GOP "frontrunner," given that -- while he still leads in delegates -- he can't seem to win decisive victories in a region of the country that is critical to Republicans' success in the general election: the South?
Romney's defenders will cite his victories in Virginia and Florida. But in Virginia, neither Santorum nor Gingrich were on the ballot and Romney still managed to give up more than 40 percent of the vote to his only challenger: Ron Paul.
Florida is heavily populated by retirees from the Northeast. In 2008, GOP presidential hopeful Rudy Guiliani's entire campaign strategy consisted of waiting around for the Florida primary, partly in the hopes that retired New Yorkers would carry him over the finished line. That didn't work out for Guiliani but it wasn't because he was wrong about who lives in Florida.
Let's remember that Romney has been criticized by some in his party as not sufficiently conservative and who, as governor of liberal Massachusetts, had to learn to "speak Democrat" to get things done. In a curious twist, he does well in those parts of the country that we can expect will go into the Democratic column on election night.
For Republicans, states like Massachusetts, Vermont, and New Hampshire are lost causes. And yet, Romney does poorly in the South, which -- with perhaps the exception of Louisiana -- tends to be painted red on election night. How is that good news for Republicans if Romney is the nominee?
2. Is it possible that a Republican can be elected president without carrying the South?
It's hard to see how. If the Republican nominee -- no matter who it is -- were to write off the Southern states, he would need to be assured of victories in other states that could offset those losses. Most of the rest of the country is already spoken for, divided up between Democrats and Republicans.
The South is the anchor of any Republican presidential campaign. If the GOP loses one or two key Southern states that it is accustomed to winning in the general election, it'll blow its shot at the presidency.
That is why nominating Romney would be a major gamble for the party, whether the Republican establishment sees it or not. They think that Romney is the "safe" choice. Not in the South, he isn't. If white Republicans aren't enthusiastic about the party nominee and don't turn out, but black Democrats do, the election night map could wind up mighty blue south of the Mason-Dixon line.
3. Will President Obama -- seeing that Romney, still the likely GOP nominee, is struggling to connect to voters in the South -- respond by putting a few Southern states in play, and make a major push to win them in the general election?
It's the smart move. And Obama, for all his failings as president, is also a smart campaigner. It would mean Democrats would have to spend more than planned on states like Alabama, Tennessee and Georgia in the hopes of turning out enough African-American voters -- and given the demographics of the new South, Hispanic voters -- to vote for Obama and swing those states to the Democratic column.
If the Democrats just made a serious pitch for Southern states, that simple act would change everything. It would put Republicans on the defensive and force them to spend money to compete in states that they thought were already in the bag.
In politics, if you have a weakness and your opponent detects it, you're probably in for a pummelling.
Mitt Romney's weakness is the South. If Republicans disregard this and make him their nominee, a pummelling they will get.
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The opinions expressed in this commentary are solely those of Ruben Navarrette.