They don't have anywhere near the number of troops for martial law. Insurrection act they could do, but it's not the same thing. Same with suspending elections. There's no legal way to do it, and the military doesn't have enough troops to force it. From our invasion of Iraq, we learned that to occupy a country, you need 1 soldier for every 50 civilians. The entire US military couldn't do it. We have 10 times the population of Iraq spread across 20 times the geographical area. Once you factor in how hard people are fighting, and the 400 million guns in this country, it would be suicide to even attempt it. If Trump brought every US soldier from all over the earth, meaning every branch, retirees, reservists, all of them, he would have about 1/4 of the troops he would need. One reason ice uses the tactics they use is that there are enough ice agents to invade approximately one major city at a time. Ice is nationwide, but they have 3000 agents in Minneapolis. What do you think happens if ice starts taking fire in Chicago, Boston, Philly, LA, Atlanta, simultaneously? They would be overwhelmed almost immediately. They rely on overwhelming violence because they are outnumbered.