By Richard Downes, Washington Correspondent

For the four candidates left in the Republican race to become the nominee for the general election later this year, today, Super Tuesday, is a big day.

It may not be the end of the world if they don’t do well, but it is close to being over if they fail to make a mark.

The polls have begun to look a little better, of late, for Mitt Romney. He must do well or the questions about his suitability will multiply. And he must do well in Ohio, which is a key state in the mid-west. Everyone you pass in the street here will tell you that no Republican has ever won the presidency without winning Ohio.

Newt Gingrich is expected to win in Georgia and Tennessee and using the million given to him by his billionaire casino mogul friend, Sheldon Adelson, he is still in the game. Ron Paul is not in the race to win but to make a mark for his particular brand of libertarianism. Rick Santorum has had a difficult time lately.

He took his campaign down the cul de sac of arguing about contraception and other social/religious issues. As various Republican commentators have pointed out, contraception is a settled social issue. There’s very little interest in it, outside of the religious fringe.

Time will tell whether he has completely blown his chances or if he can scrape a win in a couple of states. If he does win anywhere, but particularly in Ohio, Rick Santorum will have done his campaign no harm at all.