Legal Question in Constitutional Law in Florida

That's a good question. If you are a fan of the president's, you'd say absolutely. if you are not a supporter of his, you'd say just the opposite. The answer probably lies closer to "yes" than to "no". First of all, the president (not necessarily this particular president) is on duty 24/7. Even on vacation, he's expected to be able to react to anything at a moment's notice. That's why we have a military officer within footsteps of the president 24/7 with the nuclear codes; and why when the president goes anywhere its a huge operation because of the requirement that the infrastructure for him to be able to react is immediately at hand. So if he's on AF1 heading to a campaign event for HRC, ostensibly he could be doing paperwork or having a meeting aboard the plane, just as he would be in the White House.

The better question is who pays for the president's time and travel expenses when he campaigns for a candidate? We'd like to think that the candidate, and not the taxpayer, should pay 100% of the costs. That's not what really happens, partially because its so easy for the president to do something on a campaign trip that's not campaigning, but doing something presidential.

There's probably a constitutional law professor somewhere who is writing an article that nobody will read on this exact subject!

In modern time, the President is never truly away from the job. It travels with him even when he's on vacation. The same is true when he's on the campaign trail, either for himself (when seeking re-election) or for someone else. If President Obama said he would "clear" his calendar, he was speaking figuratively. He will make room in his schedule, but he won't stop serving as President.