During his big economic policy speech Monday in Detroit, Donald Trump spoke out forcefully against so-called free trade deals.

When he wasn’t being interrupted by protestors, he promised to reject the TPP, renegotiate NAFTA, and even leave NAFTA altogether if Canada and Mexico refused to play ball.

If the TPP is actually approved it will be catastrophic. That's why I have announced we will withdraw from the deal before that can ever, ever, ever happen...

I have previously laid out a detailed 7-point plan for trade reform, available on my website. It includes strong protections against currency manipulation, big problem, tariffs against any countries that cheat by unfairly subsidizing their goods, and it includes a total renegotiation of NAFTA which is a disaster for our country. A total renegotiation. And if we don’t get a better deal, we will walk away.

When he talks like that, Trump sounds a lot like, well, Trump.

No serious Republican presidential candidate has talked that way on

trade in at least a generation.

But when Trump talks about renegotiating NAFTA he also sounds like someone else.

He sounds like a certain junior senator from Illinois who way back in 2008 made criticism of NAFTA, CAFTA and other so-called free trade deals a big part of his presidential campaign. One of the reasons why I voted for him.

It’s easy to forget now, but when then-Senator Barack Obama first ran for president, he did so as an opponent of corporate-managed trade policies.

This is what he used to sound like:

Keith Olbermann: Scrap NAFTA, Senator Obama, or fix it?

Senator Obama: I would immediately call the president of Mexico, the president of Canada, to try to amend NAFTA, because I think that we can get labor agreements in that agreement right now.

Senator Obama: NAFTA needs to be amended and I've already said that I would contact the president of Mexico and the prime minister of Canada

It's absolutely critical for us to understand that NAFTA was an enormous problem. The permanent trade relations with China, without some of the enforcement mechanisms that were in there, that you voted for, was also a significant problem.

Flash-forward eight years though, and President Obama now sounds like this:

As I've said before, it means that we have to do everything we can to make sure that everybody shares in prosperity, that we have strong rules to protect workers, to promote high wages, to make sure that our citizens are getting the education and the training that they need.

But the answer cannot be to back away from trade and the global economy. It is here to stay. It's not possible to cut ourselves off

So what happened?

How did the guy who spoke so eloquently about the damage NAFTA did to manufacturing towns all across America, how did he turn into the country’s most vocal and most important supporter of the TPP?

That’s a complicated question, and there are really only two possible answers to it.

The first is that President Obama gave progressives the old bait-and-switch.

In other words, he never really wanted to renegotiate NAFTA but just said so to get elected.

So that’s one possible answer.

The other possible answer is that President Obama actually did want to renegotiate or reform NAFTA but was corrupted by big money once he got to the White House.

Either way, the story of President Obama’s “evolving” views on trade reveals a lot about our political system and what we can expect from our elected representatives.

People will say anything to get elected, and once they’re in office they’ll more likely than not follow policies that reflect what their big money donors want.

Given the reality of our post-Buckley and post-Citizens United campaign finance system, you can’t trust anybody - with the exception of maybe Bernie Sanders - to actually follow through with what they say they’re going to do.

Which is exactly why absolutely no one should believe Donald Trump when he says he says he’s opposed to so-called free trade.

I mean, President Obama said pretty much the same type of stuff when he first ran for president and look where we are now -- we’re very close to signing the biggest so-called free trade deal in American history.

And by the way, you don’t need some overarching philosophical theory of how money corrupts politics to realize that Trump is full of it on trade.

We know for a fact that when looking for running mates, the Trump campaign offered them full control over domestic and foreign policy, which, in the case of Mike Pence means that Trump will likely end up signing the TPP because Pence, like most establishment Republicans, supports the TPP.

There’s one very big takeaway from all of this: It’s time for us to start holding our politicians accountable.

There are no silver bullets in politics; there are only hard-fought victories and defeats that translate into smaller victories down the line.

So if you don’t want Hillary Clinton or Donald Trump or even Barack Obama to go back on their campaign promises after the presidential election, you’ve got to get and stay politically active and let them know.

It’s nice to dream about political saviors, but it’s even better to win actual victories by going to protests, infiltrating the Democratic Party, and organizing in your community. At the end of the day, it's really all about us and our efforts...