Forget Seth Moulton.

It’s Rep. Ayanna Pressley who keeps Sen. Eddie Markey up at night, not the challenging congressman from Salem.

That is because in a three-way race for the Senate, Pressley of Boston has a good chance of toppling Markey in the 2026 Democrat primary

That is when Markey, 79, of Malden and Chevy Chase, Maryland, will be seeking reelection to a third term in the Senate after serving in the House from 1976 to 2013.

That was when he won a special election to fill the term of Sen. John Kerry, who had been appointed Secretary of State. Markey was reelected in 2014 and again in 2020 when he defeated Joe Kennedy III.

Markey, who served in the Massachusetts Legislature before going to Washington, has been in public office longer than Moulton, 47, and Pressley, 51, have been alive.

Since all three are progressive Democrats with similar voting records, it is hard to see what issues Moulton or Pressley would use against Markey, other than his age.

If reelected, Markey will be the oldest member of the U.S. Senate. If defeated, he will have one of the biggest government pensions ever.

While Moulton has officially announced his candidacy, Pressley has not and there is no indication that she will do so rather than seek reelection.

Pressley, like Moulton, would have to give up a safe House seat to make the Senate run.

That would also mean that Pressley’s House seat, like Molton’s, would be up for grabs,

Still, outside of Moulton, Pressley is the only member of the state’s nine-member delegation to the U.S. House, all Democrats, who has not endorsed Markey, which means her option to run is open.

And her decision could be influenced by a recent poll that showed Markey beating Moulton by 45% to 22% among those polled.

The poll conducted by the Suffolk University Political Research Center for the Globe, also showed that in a three-person race, Pressley edges out Markey by 35% to 34% with Moulton fading down to 16%.

A more meaningful poll would be one pitting Markey against Pressley, but it apparently was not taken, or if taken, not released publicly.

Defeating a veteran incumbent member of Congress in a Democrat primary is no easy task, to state the obvious.

But both Moulton and Pressley did just that to begin their careers in Washington.

Moulton in 2014 ousted veteran U.S. Rep. John Tierney in the North Shore’s Sixth Congressional District and has been reelected ever since.

Pressley, then a member of the Boston City Council, in 2018 upset longtime Rep. Mike Capuano of Somerville to win the seat once held by John F. Kennedy and Thomas P. “Tip” O’Neill.

The Pressley victory was historic because she became the first black woman to be elected to the U. S. House from Massachusetts.

She could also be the first black woman elected to the U.S. Senate. The late Republican Sen. Edward W. Brooke was the first black man elected to Congress from Massachusetts.

It must be tempting.

When Pressley first got to Washington, she joined what became known as The Squad, a left-wing faction of the Democrat caucus made up of four women of color. The others are Reps. Ilhan Omar and Rashida Tlaib of Minnesota, and Alexandria Ocasio-Cortez of New York.

While Pressley was the oldest and most politically experienced of the group, it was not long before Ocasio-Cortez — known nationally as AOC — became the most famous and most important.

Now there is talk of AOC getting to the Senate by running against — and beating — fellow New York Democrat Sen. Chuck Schumer in 2028.

Pressley, if she runs, could get their first by beating Markey in 2026.

Veteran political reporter Peter Lucas can be reached at: peter.lucas@bostonherald.com

U.S. Rep. Seth Moulton has declared his run for Senate against Ed Markey. (Herald file photos)