Alexandria Ocasio-Cortez backs 2020 challenger to sitting Illinois Democrat

Rep. Alexandria Ocasio-Cortez (D-N.Y.) offered her endorsement Tuesday to Marie Newman, who is challenging conservative-leaning Illinois Democrat Rep. Dan Lipinski.

Why it matters: This is the lawmaker's first endorsement of the 2020 cycle. Ocasio-Cortez was elected in 2018 after successfully challenging incumbent Rep. Joe Crowley (D-N.Y.), who was the fourth-highest Democrat in Congress. Her backing "could turn out progressives and turn off centrists in the suburban Chicago district," writes the Chicago Sun Times.

The big picture: Newman has also received support from progressive lawmakers including Sens. Elizabeth Warren (D-Mass.) and Bernie Sanders (D-Vt.). Lipinski is a Democrat, who has, at times, acted separately from the more progressive wing of his party.

• While the congressional seat is in a safely blue district, the Democratic battle exemplifies an ongoing ideological rift between progressives and moderates, and "a reflection of the zeal of the party's progressive left to leverage its nascent power to continue targeting sitting Democrats," per the New York Times.

Go deeper: What they're saying: Alexandria Ocasio-Cortez on the 2020 candidates