In 2008, during an interview with Univision's Jorge Ramos, Barack Obama promised to introduce a comprehensive immigration reform bill during his first year as president.

He did not do that. And his failure to keep that promise set off years of very testy relations between the Obama administration and immigration activists.

In 2016, at a debate hosted by Univision and moderated by Jorge Ramos, Hillary Clinton has made the following promises:

To introduce a comprehensive immigration reform bill, including a path to citizenship for unauthorized immigrants, "in the first 100 days of my presidency"

Not to deport children

Not to deport unauthorized immigrants without criminal records

To prevent families from being separated by deportation

To "try to" reunite the families already separated by past deportations

At the risk of stating the obvious: This is a lot to promise.

All of these actions are within the power of the executive branch to take. That's not the problem.

The problem is that most of them are really big changes from existing Obama administration policy on immigration — which is already a lot more progressive than the immigration policy of the past few decades, and a lot more progressive than many of the people implementing it would like.

Furthermore, all of these (with the possible exception of the last one) are red-line promises. If a Clinton administration breaks any of them, it's going to be clear. And grassroots immigration activists are likely going to be looking very hard for any evidence that a President Clinton is breaking her immigration promises — just like they were sure to lift up any evidence in 2011 and 2012 that the Obama administration was deporting students when President Obama said it wasn't.

It took until 2014, by announcing a series of executive actions (the most prominent of which are currently under a constitutional challenge), for immigration activists to stop holding Obama's 2008 promise against him. The Obama administration can probably tell Hillary Clinton that she has just set herself a very, very tall order to fill.