Another Tuesday, another big day in this year's Presidential election. For John McCain and Mike Huckabee, it is just a matter of McCain getting to the magic number to clinch, which he might do today. For Barack Obama and Hillary Clinton, this could be the end of the line, or it could signal yet another change in direction. Here is what is at stake:

Ohio - On the Democratic side, 141 delegates awarded proportionally, 92 based on Congressional districts and 49 based on the statewide results. On the Republican side, 85 delegates awarded, with 54 awarded proportionally by Congressional district and 31 awarded as a winner-take-all to the top vote getter. Hillary is leading most of the Ohio polls, although the Zogby poll shows it as a tie. On the GOP side, McCain is up big in the Ohio polls.

Texas - For the Democrats, 126 delegates awarded proportionally based on state senate districts. In addition, a caucus will be held to choose delegates to the state and county conventions that will eventually award more delegates to the national convention. For the Republicans, 137 delegates awarded, with 96 awarded proportionally and 41 delegates available as winner-take-all if the winner has more than 50% of the vote, otherwise awarded proportionally. Hillary has regained the lead according to some of the late Texas polls on the Democratic side, and McCain leads by a large margin on the GOP side.

Rhode Island - For the Democrats, 21 delegates are available, 13 to be allocated proportionally by Congressional district and the other 8 proportionally statewide. For the GOP, 17 delegates to be awarded proportionally by Congressional district. Clinton leads in the Rhode Island polls, but not by a whole lot according to the most recent, which puts her up only 42%-37%. The only poll I have seen of the GOP race in Rhode Island has McCain up 65%-18%.

Vermont - 15 delegates are available for the Democrats, awarded proportionally statewide. For the GOP, 17 delegates will be awarded, winner-take-all. According to this poll, Obama is up 60%-34. On the GOP side, McCain leads big.

So, what to expect? Roger Simon at Politico believes Hillary can still win. I believe she can, as well, as I pointed out in a scenario I wrote last month. She needs to win big states and get this thing to the convention. At this moment, she has a slim lead in both Ohio and Texas (she also leads in Rhode Island). If she can win Ohio, Texas and Rhode Island today, she can make a powerful case that she is the candidate who can win the big states and, therefore, the candidate best able to win the general election in November. Some have said that should she win these states by only a narrow margin, she should still drop out. I think that is foolishness, and I would be shocked if she did so.

On the GOP side, it is just a matter of waiting to see if McCain can clinch.