The White House has declared that it's going to make a major move to change immigration policy through executive action — and it's expected to protect millions of immigrants from deportation when it does. But while the announcement was originally supposed to come by the end of summer, officials have been pumping the brakes. Now, the delay is official: there will be executive action on immigration, but not until after the midterm elections in November.

BREAKING: White House officials: Obama to delay immigration action until after November election. — The Associated Press (@AP) September 6, 2014

There have been two different schools of thought among Democrats about how a big immigration move before the elections would affect some key Senate races. Senate Democrats, in particular, felt there wasn't much upside to making a big announcement before the midterms.

As Greg Sargent of the Washington Post explains: "In the core red states that will decide Senate control, there are very few genuinely persuadable voters left. Base turnout will be decisive."

There aren't many Latinos in the states with the tightest Senate races, which means an immigration move wouldn't have much impact on the Democratic base. But some Senate Democrats felt that it would help the GOP turn out its base of angry conservatives upset about an "imperial presidency" and "executive amnesty." The White House has apparently decided those concerns have merit.

The question is whether the Republican base will actually be less energized now than they would have been if Obama had made a big move. Richard Trumka of the AFL-CIO and other advocates believe that the Republican base is already enraged with Obama's immigration policy, so the downside of a big pre-election move would be pretty small. And Republicans can still tell their base that Obama is planning a massive amnesty.

It's a little harder to mobilize voters over a prediction, but GOP can still run hard against what Obama "will do" on immigration. — Ari Melber (@AriMelber) September 6, 2014

This is actually the second time this year that the Obama administration has announced a review of immigration policy to lead to executive action, then delayed it. Here's the history of the long-pending review:

Between now and the November elections, meanwhile, tens of thousands more unauthorized immigrants will be deported.