Pat Toomey is one of the smarter politicians in Washington. It's how he got elected to the Senate as a Republican in Democratic-leaning Pennsylvania.

So, when Toomey makes a move you can assume it was well thought out and smartly calculated. That's why this clip -- in which Toomey says he voted for Texas Sen. Ted Cruz in today's Keystone State primary -- is important to take note of.

Toomey has been totally silent on the Republican presidential primary race since his preferred candidate, Florida Sen. Marco Rubio, dropped from the race in March. The furthest Toomey has gone since then is to say he plans on supporting the eventual nominee. So, why today? And why Cruz?

The answer to the first question is relatively easy. Today is the day when Toomey had to actively choose between Trump, Cruz and John Kasich in his home state primary. But, he didn't have to share that vote -- particularly with a Democratic tracker who, in all likelihood, follows him everywhere and who he ignores 99.9 percent of the time.

Toomey wanted it known that he had voted for Cruz.  He wanted people like me -- and the rest of the political world -- to write stories about his vote for Cruz. Or, more accurately, he wanted to make sure everyone in Pennsylvania knew he didn't vote for Trump.

In short, this was no accident. (There are very few accidents or coincidences in politics.) All of which sheds some light on the question of why Toomey voted for Cruz.  Toomey sits in a state that has voted for the Democratic candidate for president in every election between 1992 and 2012.  He won his seat, barely, in the 2010 election -- a historically good year to be running as a Republican for anything anywhere.

Toomey knows that he is going to have it very tough this fall and has to run a near-perfect race to win a second term.  He is undoubtedly chagrined at the fact that the two options for his party's presidential nominee are Trump and Cruz -- neither of which help (or come even close to helping) Toomey at the top of the ticket in Pennsylvania. But, politics is about dealing with what comes your way -- whether you want it to or not.

Toomey's decision to go public with his Cruz support is rightly understood as a lesser of two evils choice by Toomey. He has clearly decided that while Cruz is probably too conservative by several ticks for Pennsylvania voters, a vote for the Texas Senator is, in the broadest terms, defensible in a general election. And, by contrast, that Toomey believes a vote for Trump would have be indefensible -- particularly to suburban Philadelphia women who lean Republican on fiscal issues but almost certainly wouldn't vote for a GOP Senate candidate who was a public supporter of Donald Trump.

Toomey's calculations get a lot more complicated if Trump winds up winning the GOP nomination. Yes, Toomey has said he will back the nominee. But, that's easier said than done when it comes to the drag Trump might be on him downballot in Pennsylvania.  Toomey will have to answer questions daily about whether he supports Trump and Trump's policies up until the moment when he a) says, again, that he does or b) says he is planning to write in [Pennsylvania Republican political luminary] for president.

Toomey is a case study in how difficult the Cruz vs Trump dynamic is for endangered Senate Republicans. It's a series of bad choices. And selecting the least bad option is rarely something politicians relish.