Sen. Timothy M. Kaine at a rally in Miami on Saturday. (Melina Mara/The Washington Post)

Hillary Clinton is not someone who takes many risks. She is a meticulous thinker who almost never leaps before looking. That caution has not always worked in her favor, politically speaking, but it is, without question, her defining trait.

Clinton’s selection of Timothy M. Kaine, a senator from Virginia, to be her vice-presidential running mate reflects that caution — coupled with a confidence that this general-election race is hers to lose.

From the start of the vice-presidential selection process, Kaine has always been at or near the top of any list of potential contenders. The reason is simple: He checks lots and lots of the traditional boxes someone looks for in a vice president.

Kaine comes from a swing state. He has executive and legislative experience. (Before his election to the Senate, Kaine was governor of Virginia from 2006 to 2010 and mayor of Richmond before that.) He has a strong Catholic religious background. (He was a missionary out of college.) He speaks fluent Spanish. He had been vetted favorably by then-Sen. Barack Obama during the 2008 presidential campaign.

And, most importantly, Kaine is a steady presence. He has been in the national spotlight — both during the 2008 vetting and during his stint as Democratic National Committee chairman from 2009 to 2011. He knows how to handle the media, the scrutiny and the attacks that come with a high-profile perch. He is even-keeled amid chaos.

The flip side of all of this is that Kaine is occasionally — okay, often — described as “boring.” “I am boring,” he joked in an interview with “Meet the Press” host Chuck Todd last month. But the fact that Kaine is more workhorse than show horse is what commended him to Clinton. Far from being a negative, Kaine’s steadiness — call it boringness if you want — was a huge positive.

Remember that running mates tend to either reinforce or undermine the broader narrative that the presidential candidate is trying to sell. When Bill Clinton picked Al Gore in 1992, it was a doubling-down on the fresh-faced sons of the New South. (That was good.) When John McCain named Sarah Palin in 2008, it undermined his key message against Obama of experience vs. naivete. (That was bad.)

In naming Kaine, Clinton is making it clear that she favors policy chops over pizzazz, governing over glitz. She hopes that drives a very stark contrast with the showmanship and celebrity of Republican presidential nominee Donald Trump. Trump is talk, Clinton is action.

Clinton-Kaine is not the world’s most exciting ticket. That is on purpose. Clinton clearly thinks that the electoral map and the demographic realities of the country favor her and that as long as she does nothing to roil the waters, she is likely to win in November.

If Clinton felt as though she needed to either court the liberal left or more broadly shake up the race, she would have chosen someone such as Sen. Cory Booker (N.J.), an African American, or Sen. Elizabeth Warren (Mass.), a liberal icon. But Clinton did not, and, in truth, I’m not sure how close she ever came to picking anyone other than Kaine.

With her choice of Kaine, Clinton is sending a very clear message: This is my race to win, and I’m not going to take any unnecessary risks along the way that could mess that up.