There are four Republican primary contests later today: Hawaii, Idaho, Michigan, and Mississippi. These are very different states, ID and MS are red as can be, HI and MI are mostly blue, although MI has a Republican governor.
It will be interesting to see whether the Trump downward trend continues, or alternatively he scores big. Cruz has experienced a bit of a boomlet, will it persist or even grow?
I read today that Republican Party rules require the party's nominee to have won a majority of the delegates from at least eight states. This means people like Kasich and Rubio are not on track to win. Cruz will probably get there, Trump is already there. Realistically, if the GOP follows its own rules, Cruz and Trump are the only two who are likely to meet the criteria.