From USA Today:
WASHINGTON — Rand Paul and Marco Rubio have apparently concluded that politics and Senate business don't mix.
Senators are allowed to mix political and official travel and bill taxpayers for a portion of the costs, but the two GOP senators have avoided doing so while building national profiles over the past several years.
USA TODAY has reported in recent weeks that Sen. Ted Cruz, R-Texas — who has announced that he will run for president — and former senator Hillary Clinton used taxpayer funds from the Senate offices to travel around the country on trips that had a political component. Such expenditures are legal, and The Washington Post opined that the senators' use of mixed-purpose trips was "like everyone else."
But Rubio and Paul have avoided taxpayer-funded mixed-purpose trips in the run-up to the 2016 campaign season. Paul announced his presidential campaign Tuesday, and Rubio is expected to follow suit next week. Clinton is expected to announce her candidacy imminently.