New York's coronavirus-delayed primary is Tuesday — and it has the potential to throw a wrench into the power structure in the Democratic-controlled House — while in Kentucky there's a Democratic battle for the right to challenge Senate Majority Leader Mitch McConnell in November.
In New York, among those fighting primary challenges from their left are Democratic Reps. Eliot Engel, chair of the Foreign Affairs Committee; Carolyn Maloney, chair of the Oversight Committee; and Jerry Nadler, chair of the Judiciary Committee — all longtime incumbents.
Of the powerful trio, Engel, who's in his 16th term in Congress, is by far the most vulnerable. His race has become a flashpoint in the battle between establishment Democrats and the progressive wing of the party.

Democratic Rep. Alexandria Ocasio-Cortez, who represents the district next to Engel's, has endorsed his more progressive challenger, Jamaal Bowman, a 44-year-old father of three and former middle school principal who has campaigned on racial injustice and human rights.
Other progressives have followed Ocasio-Cortez's lead, with her fellow "Squad" member, Rep. Ayanna Pressley of Massachusetts, and Sens. Bernie Sanders of Vermont and Elizabeth Warren of Massachusetts, both of them former presidential candidates, endorsing Bowman, as well.
Engel has countered with his own big-name backers, including former presidential nominee Hillary Clinton, Senate Minority Leader Chuck Schumer of New York, House Speaker Nancy Pelosi of California, New York Gov. Andrew Cuomo and Rep. John Lewis, D-Ga., the civil rights leader.
"If veteran congressman Eliot Engel falls, the Democratic Party will be apoplectic," longtime New York political strategist Hank Sheinkopf told NBC News. "They'll have to deal much more with the AOC wing of the party. The left wing of the party will be better positioned, and Joe Biden will have a bigger headache the next morning."
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Maloney and Nadler appear to be on much safer ground, Sheinkopf said.
Maloney is running against three challengers, including Suraj Patel, whom she defeated in a one-on-one contest in 2018. Nadler is running against two challengers who ripped him as "all talk" on progressive issues during a NY1 debate last week, arguments that he countered by pointing to the endorsements he's gotten from Ocasio-Cortez and Warren.
Ocasio-Cortez, meanwhile, is defending her own seat from a challenger who has been using some of her own tactics against her.
Ocasio-Cortez won the seat in 2018 in a major upset over Joe Crowley, one of the top-ranking Democrats in the House. She'd argued that he spent too much away from the district focused on issues that didn't involve his constituents — the same complaints her main challenger, Michelle Caruso-Cabrera, has made against her by saying "AOC is MIA."
Because of the pandemic, Caruso-Cabrera, a former CNBC anchor, hasn't been able to knock on as many doors as Ocasio-Cortez did in 2018, and Ocasio-Cortez has a significant money advantage, having raised over $10 million. That's five times more than Caruso-Cabrera has raised.
Primary day will also include a special election delayed from April to fill the upstate New York seat left vacant by the resignation of Republican Rep. Chris Collins, who pleaded guilty to insider trading last year.
The pandemic is looming over the primary in other ways.
Cuomo issued an executive order in April calling for absentee ballot applications to be sent out to all voters in the state in a bid to make voting during the pandemic safer. In New York City, the city Board of Elections has sent 679,000 ballots to voters who've requested them.
Statewide, over 1.6 million absentee ballots have been sent out, according to the state Board of Elections. In 2016, 115,000 people voted absentee in the presidential primary.
What the surge in absentee voting means for the primary is unclear, Sheinkopf said.

