The GOP: The Democratic race is much closer than the Republican, but the Republicans have winner take all races in many states while the Democrats do not. April has three such high stakes contests, Wisconsin's 42 delegates being decided this Tuesday and winner take all primaries in Delaware (16 delegates) and Maryland (38 delegates) three weeks later on the 26th. There are also two big states, New York on April 19th for 95 delegates and Pennsylvania on the 26th for 71 delegates. Pennsylvania can be winner take all, but I do not know what the threshold for that is.
Recent polling in Wisconsin favors Ted "The Snake" Cruz. There are four polls from late this month and Cruz leads in three, while Trump is the favorite in the other. The most interesting progression in he polls is from the Marquette Law School poll, which has polled the state six times since last August. Here are the leader and second place candidates in those polls.
August 2015: Walker 25, Carson 13
September 2015: Trump 20, Rubio 20
November 2015: Carson 22, Rubio 19, Trump 19
January 2016: Trump 24, Rubio 18
February 2016: Trump 30, Rubio 20
March 2016: Cruz 40, Trump 30
I should note that Cruz was in third place in the earlier polls this year, but the numbers look like nearly all of Rubio's support switched over to Cruz when Rubio quit.
The Dems: There are also four polls from late March dealing with the Wisconsin race. Bernie Sanders leads in three and Hillary Clinton leads in the other. All the Democratic races are proportional, so unless his margin of victory is much larger than it currently looks at around 5 points, he will gain some press and momentum but precious few delegates. After that, the Democrats have a caucus in Wyoming on the 9th, a style contest that usually favors Sanders, then the big prize of New York on the same date as the Republican contest, April 19th.
I will report again before the New York contest.