The arrival of migrants in big cities is forcing Democrats to change their immigration politics

A version of this story appeared in CNN's What Matters newsletter. To get it in your inbox, sign up for free here.

President Joe Biden says he's been forced to violate a campaign promise by adding some new construction to Donald Trump's border wall.

Big city Democratic mayors are angrily demanding more engagement from the Democratic president to help deal with a wave of migrants seeking asylum. One of them - New York Mayor Eric Adams - is in Latin America this week.

Immigration reality is scrambling the normal immigration rhetoric in uncomfortable ways for Democrats, who generally want to appear welcoming but appear to be taking a harder line along with their new positions.

Here's how CNN White House reporter Priscilla Alvarez explained Biden's about-face during an appearance on the network Thursday:

Alvarez: This boils down to the administration running up against a deadline. A source that I spoke with this morning said that the 2019 congressionally appropriated funds for a border barrier had to be used by the end of fiscal year 2023.That means the administration had to make a choice - they either use the money or they don't use it, and they decided they're going to use it for these border barriers in South Texas.

Read her full report.