Look at the only lawmaker who has become president in the last half-century. Barack Obama did almost nothing in his brief time in the Senate. His career in the world's greatest deliberative body consisted mainly of showing up, becoming immediately dissatisfied and looking for something better.
Obama never took a leading role crafting any piece of momentous legislation. And some of the things he did do, like voting against raising the debt ceiling and voting to filibuster a Supreme Court nominee, came back to bite him when he moved into the White House. But mainly, Sen. Obama held to the same arm's length, disengaged philosophy that led him to vote "present" 129 times in the Illinois legislature.
If the plan was to move up, it worked spectacularly well.
On the other hand, look at the most recent senator who ran for president with a record of passing big legislation. John McCain led a crusade for campaign finance reform and tried hard, if unsuccessfully, to enact immigration reform in 2006 and 2007. That kind of work forces a lawmaker to take stands, which can lead to making enemies, which can lead to trouble in his own party. It doesn't lead to the White House.
So now Marco Rubio, a presidential hopeful, is all-in for immigration reform, with all the potential for disaster that entails. Why is he doing it?
Obviously, Rubio has a personal interest in the topic. The son of Cubans who came to the United States, his life was shaped by immigration. And he represents Florida, where 23 percent of residents are of Hispanic origin. So it's important to him, and to many of his constituents.
"Marco isn't doing this because of politics," says Rubio adviser Todd Harris. "If politics was all that mattered, it probably would have been easier to do nothing. He's doing it because our immigration system is broken." Citing problems with border security, visa security and 11 million immigrants here illegally, Harris adds, "There are a lot of reasons why he supports immigration reform, but none of them have anything to do with politics."
Without suggesting that any of that is untrue, it is nevertheless a fact that politicians consider the political effects of the things they do. So how might Rubio see the upsides and downsides of taking a leading role on a particularly hot-button issue?