Washington (CNN) The American Health Care Act is out of the House. The action now moves to the Senate, where President Donald Trump's attempt to overhaul the health care system faces a far more perilous fate.

The focus will be almost entirely on the Republican side as Senate Majority Leader Mitch McConnell tries to craft a bill that can win the votes of 50 of the 52 GOPers. (It's hard to see -- at least right now -- any Democrat voting for any sort of health care bill.)

Each one of those 52 is, obviously, important. But some are more important than others. Below is my list of the seven senators to watch, the people who are likely to not only be front and center on the bill over the next few weeks but could well hold its fate in their hands.

1. Lamar(!) Alexander

Sen. Lamar Alexander of Tennessee speaks to reporters on Capitol Hill in 2013.

Alexander is important for three reasons: He's the chairman of the Senate Health, Education, Labor and Pensions (HELP) Committee, he's from a state that would be heavily impacted by the changes made to the pre-existing conditions mandate in the House bill and he's someone well positioned, as a former member of party leadership, to bring warring factions within the GOP conference together.