With the reality of Donald Trump as the party's most likely presidential nominee beginning to (finally) sink in, some congressional Republicans are taking steps to ensure that the real estate mogul doesn't torpedo their chances of keeping their majorities in the House and Senate.

Establishment Republicans and their big-money allies are rushing to build a multistate defense system to protect Senate and House candidates, fearing that the party could lose its hold on Congress if Donald Trump is at the top of the ticket in November. ...
... The efforts are being driven by major players such as the Koch brothers’ political network, which has already begun laying groundwork in Colorado, Ohio and Pennsylvania, along with the Crossroads organizations and the U.S. Chamber of Commerce.

If you are Sens. Patrick J. Toomey (Pa.) or Rob Portman (Ohio) or Kelly Ayotte (N.H.) or Mark Kirk (Ill.) or Ron Johnson (Wis.), the news of this effort will be a big relief after months of worries about what Trump might do to your chances of holding your Senate seat in a swing — or Democratic leaning — state. All politics is local! you'll tell yourself. I don't need to own everything Trump says or does! I have my own base of support! People know me! People like me!

To which I say: Probably not. The idea of running away from a toxic (or potentially toxic) nominee seems like a sound and achievable one. It just never works.

Congressional Democrats running for reelection (or election) in the 2010 and 2014 midterms learned that lesson — over and over again. In each of those elections, the Affordable Care Act, and President Obama's dipping popularity because of the controversy over it, hung like an anvil over Democrats' heads. And they tried hard to run away so it wouldn't crush them.

This ad, from then-Rep. Earl Pomeroy of North Dakota in 2010, is illustrative of how Democrats tried to get away from the Obama problem.

He literally says "I am not Barack Obama" in the ad! Did it work? Not even close! He lost by 10 points to a Republican named Rick Berg whose entire campaign argument was premised on the idea that a vote for Pomeroy was a vote for Obama's agenda.

Pomeroy was far from alone in trying to run from Obama and failing to do so. Democrats lost six Senate seats in 2010 and nine in 2014. They lost 63 House seats in 2010 and 13 in 2014. In the 2010, 2012 and 2014 elections combined, Democrats lost 83 House and Senate seats. That's stunning.

The one obvious exception to that rule was Joe Manchin, who was elected to the Senate in 2010 despite the fact that Obama was deeply unpopular in his home state of West Virginia. Manchin, like so many Democrats trying to get away from Obama in both 2010 and 2014, ran an ad distancing himself from many of the national Democratic Party's policies, including on gun control and the environment.

He shot a hole in the cap-and-trade bill!

It worked for Manchin, who beat a self-funding Republican businessman by 10 points. Why? Because Manchin had a well-known brand as a conservative (a.k.a. non-Washington) Democrat in the state long before he decided to run for Senate. Manchin had spent the previous six years as the state's governor and before that had been secretary of state and served in the state House and the state Senate. People knew him. They knew he wasn't an Obama clone.

That's a luxury that very few politicians enjoy — whether because they haven't served as their state's governor, their state is too big to have a well-known brand throughout it or they just haven't made that big an impression on voters. And, if you are running for the House — instead of the Senate — it's a near-certainty that your constituents, including plenty who have voted for you in the past, have no real clue about you.

Which is what makes running away from someone like Trump so, so difficult. For most voters, the two parties are like the Borg from "Star Trek". If the leader of the party — a.k.a. the presidential nominee — thinks something, then everyone with an "R" after his or her name must think it, too. Even when presented with direct evidence that not every Democrat agreed with everything Obama did — Pomeroy's ad! — voters didn't care. Pomeroy was a Democrat. Obama was a Democrat. Done and done.

That's the dilemma any candidate or group hoping to distance from Trump faces. It's exacerbated by the fact that unlike 2010 or 2014, this is a presidential cycle, so Trump's name will actually be on the ballot — making it that much harder to persuade voters that you aren't like him. And there is the fact that Trump is fundamentally — and proudly — unpredictable, meaning there is no real way for a candidate trying to run away from him to develop a plan to do so.

Attempts to get out from under what is presumed to be a sinking ship are as old as politics itself. So are the failures of those attempts.