In the case of some Democrats, like President Barack Obama, it looks like us taxpayers pay a significant fraction of the costs. As Mark Knoller of CBS News noted the other day,

Under Federal Election Commission (FEC) rules, the government must be reimbursed for parts of presidential political travel.

“When a trip is for political or unofficial purposes, those involved must pay for their own food and lodging and other related expenses, and they must also reimburse the government with the equivalent of the airfare that they would have paid had they used a commercial airline,” states the Congressional Research Service in a 2012 analysis of “Presidential Travel: Policy and Costs.”

Further, when a presidential trip includes both political and official appearances, the White House is permitted to prorate the reimbursable costs.

However,

As President Obama embarks Thursday on a three-day Democratic fundraising trip to California, the White House again refuses an umpteenth request from CBS News for the political travel information.

[R]epeated requests are turned down for a breakdown of the costs and an explanation and specific examples of how the White House calculates how much is paid by taxpayers and how much must be reimbursed to the government by the Democratic National Committee or others.

The Obama White House justification? They insist that prior administrations also have refused such disclosures.

There’s that Democrat morality with which we’re all so familiar: the rightness or wrongness of a thing isn’t inherent in the thing; it’s entirely in whether someone else did first, or is doing it also.