Nevada has one of the largest Hispanic populations of any state — more than a quarter of the state's population and 18 percent of its voters in 2012 were Hispanic, and they voted overwhelmingly for Democrats in the last few elections in the state, giving President Obama comfortable wins in both of his elections and nearly costing Sen. Dean HellerDean Arthur HellerMcConnell: Midterms will be 'very challenging' for GOP Singer Jason Mraz: Too much political 'combat' in Washington Trump gives GOP midterm pep talk MORE (R-Nev.) his own election in 2012.

Heller, who has a more conservative record on past immigration efforts, including opposition to the DREAM Act, called the bipartisan immigration proposal introduced this week a "reasonable starting point" in a statement earlier this week.

The Nevada state GOP is an unusual one — after years of disorganization it was taken over by Ron Paul supporters last year who have often sparred with the national party, going so far as to put up billboards attacking Mitt Romney during last year's election while Romney and the Republican National Committee built a "shadow Republican Party" in the state to work around them. But McDonald seemed to bury the hatchet with the national party when he endorsed RNC Chairman Reince Priebus for reelection at their winter meeting earlier this month.