As of Sunday night, realclearpolitics.com averages saw Obama ahead of Hillary Clinton in Texas 46 to 45 percent and Clinton ahead of Obama in Ohio 47 to 43 percent. In other words, either candidate could win either or both races, though Clinton is probably really just a little ahead in Ohio. So how do you explain why Obama paid a campaign visit to Rhode Island, which, along with Vermont, also votes Tuesday? Answer: to keep Clinton from winning three out of four contests March 4. Obama is obviously well ahead in Vermont. But the only three February polls in Rhode Island, two of them by polling operations unfamiliar to me, show Clinton leading 46 to 35 percent. That's a lot more undecideds than you'll see in most polls at this stage. If I were an Obama strategist, I might think a Rhode Island visit worthwhile if it had any chance of swinging voters toward Obama (or spurring young voter turnout for him in a state where presidential primary turnout has traditionally been minuscule). An Obama win in Rhode Island would eliminate the chance that Clinton could win three of four March 4 contests and get whatever claims of momentum that might generate.