A sitting president has immunity from prosecution and civil liability in general. Then it starts to get complicated. Some argue that there is absolute immunity - shorthand definition for that would be "total immunity for everything that happens while the president is a sitting president. Doesn't mean they cannot be prosecuted eventually if you remove them through impeachment. But the law is somewhat unsettled. And then there differences between criminal and civil immunity that have to be sorted out. And then there is the question of whether the immunity is just while in office or even while they are out. The argument being that you can't make a president a sitting duck for ticking time bombs to just get hammered legally for everything he did in office. And the counter argument that you can't just give him a get out of jail free card for everything. And so the arguments go. In general there is at least the agreement (and some case law) that a president has "qualified immunity." meaning that he has immunity for any actions that are reasonably related to the fulfillment of your presidential duties, even if you do not agree with them. So, for example you cannot be prosecuted for ordering the killing of an American citizen, which Obama did when he killed an American terrorist. But if Obama had ordered the killing of his chef because he was porking his wife, he could be prosecuted. That is the general lay of the land and the issues. So Trump - if he cannot win on the absolute immunity argument- wants to at least win on the "qualified immunity" argument and then successfully convince a jury that his "involvement" in the electoral process was part of his duties as president to ensure fair elections rather than corrupt meddling. As I said earlier, at a minimum he is just making argument to delay his trial until after the election. Like dat.
There are multiple checks on a US President. Just look at President Richard Nixon and Watergate. Clinton went thru an impeachment trial, Trump went thru 2 impeachment trials. The difference between the two is Clinton lied under oath and the charges on Trump is bogus. Unfortunately, what the US needs is a mechanism for abuse of power which a lot of Democrats are guilty of. Without the deep state protecting such abuses, these Democrats should have been charged and locked up in jail for others not to follow. Look at the district attorneys in various states, charging Trump over and over with the goal of bankrupting him and prevent him from running for US President. It is too obvious for anyone to miss that these are abuses of power on top of wasting tens of millions of dollars to persecute Trump.
Indeed. The Clinton situation brings in yet another complexity. People point out that Clinton ended out paying a fine and was disbarred for a few years as a penalty for perjury while he was in office so this confirms- allegedly- that a president is not immune. Not really. Clinton was never indicted. He accepted a plea deal to get the thing over with, and the government was also interested in a plea deal to get it over with to avoid all the unsettled issues that trying to indict him and try him would involve. So a scenario where a defendant/president accepts a plea deal is not much of a test of the immunity issue.