Will success create more headaches for Democrats than failure does for Republicans? Answer: no, but it doesn’t mean that the surprise win of Conor Lamb in PA-18 on Tuesday has provided a kumbaya moment for his party. In fact, as Politico’s Heather Caygle reports today, it appears to have touched off a civil war on the Left between progressives and moderates over what the win means for November.

Moderates claim the win shows that Democrats need to dump progressive and aging party leadership if they want to win back turf they lost to Republicans eight years ago:

“He didn’t run on an identity politics, one-size fits all message,” said Rep. Kurt Schrader (D-Ore.), co-chairman of the Blue Dog PAC, the fundraising arm for the conservative Democratic coalition. “He ran on the Blue Dog message.”

For the Blue Dogs, Lamb’s successful center-left campaign is proof that the Democratic Party’s “big tent” mentality is still a winning electoral strategy, despite an aggressive push from liberals for candidates that more closely adhere to the progressive purity made popular by the likes of Sens. Bernie Sanders (I-Vt.) and Elizabeth Warren (D-Mass.). …

Moderate Democrats say the upset in Pennsylvania shows it’s obvious Lamb’s playbook is what other candidates should mimic in those districts. “This is not a new thought,” said [Rep. Gerry] Connolly. “That’s exactly what we did in ’06 and ’08,” when Democrats won and kept the majority.

Progressives, however, claim that Lamb’s win only proves that Democrats can win by simply “doing no harm” to the core progressive agenda:

“Conor Lamb basically did no harm on economic issues,” said Adam Green, a leader of the Progressive Change Campaign Committee.

“Regardless of how progressive one thinks he is,” Green continued, “if Democrats can win in the district that Trump won by [20] points, there is zero excuse for running on corporate or conservative values in the dozens of districts that Hillary Clinton won or that Trump barely won.”

Who’s right? Perhaps Democrats should ask themselves how they lost these seats in the first place. They went hard Left in the first two years of Barack Obama’s presidency, and never recovered in legislative elections — not just at the national level, but in state legislatures, too. They have celebrated a pickup of a few dozen state legislative seats over the past year, but they lost nearly a thousand seats between 2010 and 2016. They lost those seats in areas outside of their current ideological bunkers in the urban cores and coastal enclaves, where progressives have taken control of the party’s leadership.

This was part of my point in my column for The Week. Candidates matter, and it’s very unlikely that Democrats will have too many Lambs — and their national messaging will likely bury the few they do nominate:

House Speaker Paul Ryan later joked that a conservative won the election in PA-18. He’s not that far off the mark. Democrats want to make the midterms a referendum on Trump, gun control, impeachment, and their opposition to Trump’s tax cuts. It’s tough to see Lamb’s win as a harbinger for Democrats when he won by contradicting some of the campaign message they plan to use. Lamb had the advantage of running while Democrats could tune their message specifically to help him out. Would he have won in November with Democrats hammering those themes on national ad campaigns and talking-head shows?

Time’s Philip Elliott wondered the same thing earlier this week:

But the bigger fight in 2018 is unlikely to be a carbon copy of what narrowly happened in Appalachia for a number of reasons. For one, Democrats avoided a messy primary fight in picking Lamb, a Marine veteran who secured the nomination by winning over 319 Democrats’ backing in a high school gym filled with 554 activists back in November. In other scenarios, an energized activist base on the Left — populated by newcomers to the process who demand ideological purity — may have prevented Lamb from winning the nomination had there been a real contest. In recent weeks, more than a few progressive activists grumbled that whether Lamb won or lost, another white male who wasn’t a full-throated supporter of abortion rights would represent the district. (Lamb said he supported abortion rights but was personally opposed to the legal procedure, a stance that matches Democrats’ 2016 VP nominee Tim Kaine. Republicans called Lamb’s position “pro-life-ish.”)

At the same time, Lamb steadfastly avoided nationalizing the race and brushed off most questions about Trump. While liberals are largely united in their disdain of the President, Lamb gamely avoided moving him to center stage. Many of the loudest voices on the Left have tried to cast 2018 as a referendum on Republicans’ national agenda. Instead, Lamb kept the focus at home and talked about policy areas that matched the voters. …

Former Congressman Rahm Emanuel — now the Mayor of Chicago — was the master at this when he ran the Democrats’ campaign committee in 2006. He sought out candidates who were tailored to the districts, even if they were afield from party orthodoxy on issues such as guns, abortion and unions. Democrats netted 30 seats that year, enough to elevate Nancy Pelosi to the House Speaker role. The price to pay was a caucus with moderates known as Blue Dogs. (Most of them are now gone.)

But the Emanuel approach is not in favor among the activists who are demanding purity. Need proof? The California Democratic Party declined to endorse Sen. Dianne Feinstein’s bid for a sixth term because she’s seen as too centrist. She is likely to face another Democrat, state Senate President Kevin de León, in a head-to-head race this November.

They might still stumble into a majority while waging this civil war. The margin is now down to 23 seats, the new Pennsylvania map may give them three to five more seats, and first-term presidents generally do poorly in midterms. While the RNC is vastly outperforming the DNC, Republican incumbents have fallen behind on fundraising. It’s not looking good for the GOP, but if Democrats can’t figure out how Lamb won, they could well end up snatching defeat from the jaws of victory yet again under Nancy Pelosi’s leadership.