As I've done since Super Tuesday, I'll be using survey data to estimate how the delegates will be allocated on March 4th. For the most part, these estimates have been fairly accurate (see here and here). For Ohio and Texas, I'm using the Pollster.com average of the recent surveys conducted in each state. In Rhode Island and Vermont, the only recent polling I've found was conducted by American Research Group last week. While American Research Group surveys have often produced odd results (most recently in the days leading up to the Wisconsin primary), it is all we really have in those states right now. The estimates for the March 4th states are presented in the figure below:
These estimates show that Clinton would pick up a net gain of about 20-25 delegates on March 4th. By most counts, Obama presently holds about a 150 delegate lead among pledged delegates, which means he would still hold more than a 100 delegate advantage over Clinton after the March 4th primaries.
However, there are three reasons to be cautious about these estimates. First, we are still over a week away from the primary date, and a lot could change in that span of time. Second, at least in recent primaries, the polling has tended to underestimate Obama's support. This was not only the case in Wisconsin, but also in the Potomac primaries. It is unclear whether that will be the case on March 4th as well.
Third, and perhaps most importantly, the Texas system is quite complicated and it is not easy to estimate how things will turn out there. They use a primary-caucus hybrid, which is explained in their delegate selection plan (summarized on p. 32 of the document). Essentially, 126 of Texas's pledged delegates will be allocated according to the results of the primary. However, on the night of the primary, Texas will also hold precinct caucuses. Those caucuses will eventually determine the division of the remaining 67 pledged delegates. Obama's strength in caucuses is well-known by now...he has been winning caucus events by 2-to-1 margins. If this advantage holds up in Texas, then Obama could come out of the state with a lot more delegates than the polling suggests.
I will update these predictions over the the next week and a half as we get more polling in these states.