Republican leaders have been vocal about their differences with Trump. House Speaker Paul Ryan (R-WI) has had to admonish Trump's proposal to ban Muslims as well as Trump's support from former KKK leader David Duke. Senate Majority Leader Mitch McConnell (R-KY) has repeatedly expressed concern Trump isn't polished or disciplined enough to be a successful nominee.
Trump has made some inroads. Sen. Bob Corker (R-TN) will join Trump Tuesday in a rally in North Carolina. And Trump met with Sen. Joni Ernst (R-IA) on the Fourth of July, fueling some speculation he is courting her to be his running mate.
In the background of the Trump meeting on Capitol Hill Thursday, however, is still mounting concern that Trump endangers vulnerable Republican senators and congressmen seeking re-election in 2016. Not only has Trump's blunt rhetoric frustrated Republicans, his lack of fundraising prowess could have a major impact on down ballot candidates who traditionally count on a presidential nominee to build grassroots and get out the vote operations in swing states.