If last night's Democratic primary debate in Houston taught Americans anything, it's that the Democratic Party will survive without Bill de Blasio looming behind a podium. Beyond that, there is little sign of resolution in the turf war between the resurgent liberal base and more moderate power brokers.

For those clinging to the dwindling weeks before 2020 presidential politics becomes an unavoidable media juggernaut, Joe Biden entered yesterday's debate in Houston as a frontrunner in search of a compelling message. It isn't clear he succeeded.

In late May, Biden was the first choice of over 40 percent of Democratic voters. Today that margin has eroded to 29 percent. A recent RealClearPolitics polling average gave Biden a healthy 11-point lead over Elizabeth Warren. But Warren's surging numbers - and the huge difference in enthusiasm between Biden and Warren voters - have been a consistent source of heartburn for Biden boosters.

Warren's unexpectedly strong performance during the evening's foreign policy segment will reassure voters who find Biden's established international credentials comforting after years of Donald Trump's haphazard Twitter diplomacy.

Warren confidently outlined the limitations of "bombing our way to victory" overseas, and stressed her consultations with military leaders on the long political road to Afghan stability. She personalized an opaque issue by drawing on her past trips to Afghanistan with the late Sen. John McCain, explicitly making a bipartisan connection to one of the few Republicans held in regard by Democratic voters.

Warren held her own throughout the evening, refusing to fall for a GOP talking point masked as a question about hiking middle class taxes to pay for her health care plan. In a response that should be memorized by all Democratic candidates by now, Warren reminded moderator George Stephanopoulos - and Biden - that Americans will spend significantly less on health care than they do today, leading to a large net savings for consumers even if taxes rise slightly.

South Bend Mayor Pete Buttigieg also stood out during the foreign policy segment. On a question about whether he would maintain Trump's trade war with China, Buttigieg chastised Trump for his directionless approach. "Our allies take note of the inability of the United States to keep its word or follow through on its plans," Buttigieg said.

Buttigieg's response is part of a larger attempt to reconsider what makes America great. That greatness isn't measured solely in our ability to project our influence globally, Buttigieg argues. What matters most is the message American influence projects. On issues from trade to Afghanistan, Buttigieg's worldview is a rejection of the transactional Trumpism that has cost America strategic relationship and sapped trust in our diplomacy abroad.

The moderators asked several questions about how the candidates would address gun violence, which was appropriate given that the debate was held in a state where many Texans still grieve recent acts of mass gun violence in Odessa and El Paso. The topic prompted some of the strongest unity of the evening. Julian Castro's call for federal gun registration drew immediate support from Warren and the rest of the field. Beto O'Rourke received sustained applause for a call to confiscate AR-15s. Whether either Texan will be in the race long enough to flesh out such bold proposals remains to be seen.

Especially shocking is what was not discussed in Houston. Despite nearly three hours of questions, including one softball about having the "resiliency" to be president, no one mentioned Donald Trump's ongoing war on women. There were no questions about Trump's recent change to Title X, effectively cutting off federal funds for family planning services that even dare talk about abortion or contraception. There was silence on anti-Roe v. Wade test cases bubbling up in Republican state courts. The sharp rise in violence against transgender Americans didn't merit a single sentence.

For a field competing to outdo each other in progressive core issues, women and transgender Americans found themselves largely invisible. That isn't a coincidence - this is also the first debate without New York Senator Kirsten Gillibrand, who made women's issues the centerpiece of her campaign and multiple debate appearances.

The Democratic contenders, perhaps remembering the ugly moments from July's freewheeling debate, took pains to remind viewers that they agree on most issues. But 2020 voters aren't looking for unanimity. They want leadership.

With bold progressive ideas on issues from gun safety to education reform, Democratic presidential contenders are finally starting to sound like Democrats again. By rejecting the idea that we must choose between progressive principles and electoral victory, Warren and Buttigieg have tapped into the same reservoir of idealism that turned Robert F. Kennedy, Franklin D. Roosevelt and Barack Obama into generational leaders.

Max Burns is a veteran Democratic strategist and senior contributor at Millennial Politics. He can be seen on Fox News, Fox Business, and Bloomberg Radio. Follow him on Twitter @TheMaxBurns