What does Donald Trump think about Republicans maintaining their Senate majority?

"Well, I'd like them to do that. But I don't mind being a free agent, either," Trump replied when that question was posed to him.

As the presumptive Republican presidential nominee, Trump is set to become the titular head of the party at the GOP convention in Cleveland. This often entails campaigning for down-ballot Republicans.

Trump entered into a joint fundraising agreement with the Republican National Committee, raising some money for the party. But he is heavily reliant on the RNC for his national campaign apparatus, which makes Republicans running for other offices nervous they won't receive the support they need.

There are currently six Republican incumbents running for re-election in states Barack Obama won in 2012: Sen. Mark Kirk of Illinois, Sen. Kelly Ayotte of New Hampshire, Sen. Ron Johnson of Wisconsin, Sen. Marco Rubio of Florida, Sen. Pat Toomey of Pennsylvania and Sen. Rob Portman of Ohio. Some of these candidates' fortunes depend in part on how well Trump does in their states in November.

Both Ayotte and Johnson have offered tepid support of the nominee whereas both Kirk and Rubio are clearly at odds with Trump. Last Thursday Senate Republicans had a tense meeting with Trump, where he told them if they didn't support him they'd be "supporting Hillary."