Pelosi and her allies were able to unite the left behind her speakership in part by painting Moulton, a white male Iraq War veteran and member of the business-friendly New Democrat Coalition, as an ideological foe of the new progressive guard in Congress.

Moulton led a challenge to Pelosi’s speakership after the 2018 midterm elections that drew staunch opposition from Pelosi’s ideologically eclectic bloc of loyalists, including the most strident House progressives ― and even prompted some blowback from Moulton’s constituents.

“Our leadership is failing on two counts: Dividing our caucus and being unwilling to start impeachment proceedings against Donald Trump,” Moulton said. ”And that was most evident this weekend, because all of this ridiculous infighting in the House pales in comparison to what this White House is doing.”

Moulton, in an interview with HuffPost on Monday, reiterated his campaign trail refrain blasting Pelosi and her lieutenants for failing to initiate an impeachment investigation against President Donald Trump .

Rep. Seth Moulton (D-Mass.), a long shot candidate for the 2020 Democratic primary , blamed failed House Democratic leadership for the escalation of a public feud between House Speaker Nancy Pelosi (D-Calif.) and the four progressive freshman lawmakers known as “the Squad.”

Moulton, 40, always argued though that his problem with House leadership was generational, rather than ideological in nature. He sees Pelosi’s efforts to marginalize Reps. Alexandria Ocasio-Cortez (N.Y.), Ilhan Omar (Minn.), Ayanna Pressley (Mass.) and Rashida Tlaib (Mich.) as part of her broader unwillingness to elevate younger Democrats and incorporate their perspectives.

“This is why I spent my political career fighting for a new generation of leadership in this country,” Moulton said.

Moulton failed in his efforts to thwart Pelosi’s speakership in early January, as well as the ascension of Pelosi’s top deputies, House Majority Leader Steny Hoyer (D-Md.) and House Majority Whip Jim Clyburn (D-S.C.). In exchange for his support and the backing of his small group of rebels, Pelosi agreed to cap speakerships at four two-year terms. The fourth term would require two-thirds support from House Democrats.

Moulton, who unseated then-Rep. John Tierney in a Democratic primary in 2014, has had difficulty gaining traction in his presidential run. Having jumped into the race in late April, long after many of his rivals, Moulton did not meet either the polling or fundraising thresholds to qualify for the first Democratic presidential debate in Miami last month. Moulton raised $1.2 million in the second quarter of 2019 from 17,000 individual donors, a sum that would be impressive for a House re-election bid, but is paltry in the context of a presidential race.

The top five fundraisers in the Democratic presidential primary ― former Vice President Joe Biden; South Bend, Indiana, Mayor Pete Buttigieg; and Sens. Elizabeth Warren (D-Mass.), Bernie Sanders (I-Vt.), and Kamala Harris (D-Calif.) ― raised more than $10 million each over the same period.

But Moulton’s self-styled career as a House maverick and Pelosi critic may fare more favorably than his White House bid.

In addition to faulting Pelosi for her disparaging comments toward the “Squad,” Moulton’s support for impeachment, which dates to December 2017, also puts him on the same side as his more progressive colleagues. At a Monday press conference responding to Trump’s racist comments toward the Squad, Rep. Omar said recent events had only strengthened the case for impeachment.

The questions of generational representation and age are major sources of tension in the House where seniority rules the roost and Democrats in safe seats have been known to wait decades to obtain committee chairmanships and other top posts. As a result of the hierarchical system, many older Democrats who personally disagree with leadership ― either from the left or the right ― are often more reluctant than their younger colleagues to publicly challenge them, to say nothing of Capitol Hill’s unwritten norms and traditions.

But even by the staid standards of Congress, House Democratic leaders have proven less willing to cede ground to newcomers than their Republican counterparts. Pelosi, who has led House Democrats since 2002, is 79; her deputies, Hoyer and Clyburn, are 80 and 78, respectively.

A number of emerging stars making their way up the ranks of House Democratic leadership have found the pace of advancement frustrating and left the chamber to seek higher office. Chris Van Hollen, 60, a veteran Maryland Democrat, had been ascending the ladder of power in the House for the better part of a decade, but ultimately chose to run for Senate in 2016, where he currently serves. The same year, then-California Rep. Xavier Becerra, 61, left his post as chairman of the House Democratic Caucus to run for California attorney general, a title he currently holds.

Moulton accused Pelosi and the other Democratic leaders in the House of failing to create space for newer, younger lawmakers in the leadership ranks. He did not want to be speaker himself, but he had hoped to make room for someone like Rep. Karen Bass, a 65-year-old African-American from California.

“A fundamental responsibility of leadership is to prepare the next generation of leaders,” he said.