Alabama Senator Jeff Sessions endorsed Donald Trump at a rally today.

The endorsement is viewed as a blow to Ted Cruz, who often cites Sessions to bolster Cruz’s immigration bona fides.

The Washington Post reports:

“Politicians have promised for 30 years to fix illegal immigration. Have they done it? Donald Trump will do it,” Sessions said at the Madison City Schools Stadium, where thousands gathered to hear Trump speak. “I’ve told Donald Trump this isn’t a campaign, this is a movement.”

The endorsement represents a major blow to Sen. Ted Cruz (Tex.), one of Trump’s two chief rivals for the Republican nomination. Cruz has touted his strict positions on border security and deportation, leaning on his strident commitment to conservative ideology as a key rationale for his candidacy. In the run-up to the March 1 Super Tuesday primary elections, Cruz has tried to undermine Trump’s conservative bona fides on immigration reform, characterizing his plan as “amnesty.”

So what’s the significance of this endorsement?

I think it’s significant because it helps solidify Trump’s hold on his roughly 1/3 of the Republican electorate at a time when Trump is under increasing attack. But I don’t think it expands the Trump vote.

With Rubio, Cruz and Kasich still dividing the non-Trump vote, 1/3 may be enough to win the nomination, particularly once we get to winner-take-all states after Super Tuesday.

The interesting thing to me was not the immigration angle, but how much of the endorsement went to a general anti-globalization agenda. In this sense, the Trump wing of the Republican Party and the Bernie Sanders wing of the Democratic Party have much in common.