Now that Beto O’Rourke is looking at a presidential campaign, he is coming in for a flurry of hits from the left.

The criticism — ranging from O’Rourke’s membership in the centrist New Democrat Coalition to his acceptance of campaign money from oil industry employees — has so far been confined largely to social media, newspaper opinion pages and online message boards. But as O’Rourke considers running for president in 2020, his potential opponents are quietly taking stock, plotting lines of attack they believe could weaken the Texas congressman in a crowded primary field.

Surveying the likely skirmish awaiting O’Rourke, one Democratic strategist working with a rival campaign told POLITICO, “Trotsky got killed with an ice pick.”

O’Rourke simultaneously shrugged off — but further fueled — the criticism Friday by sidestepping the opportunity to embrace the progressive mantle after a town hall meeting here. His eschewing of partisan labels comes even as he approaches a Democratic primary that is tilting increasingly to the left.

Asked if he is a progressive Democrat, O’Rourke told reporters, “I don’t know. I’m just, as you may have seen and heard over the course of the campaign, I’m not big on labels. I don’t get all fired up about party or classifying or defining people based on a label or a group. I’m for everyone.”

O’Rourke’s supporters view the criticism from progressives as limited, and his colleagues have said privately that it does not bother him. But in a through-the-looking-glass experience, supporters of O’Rourke have been pressed to reiterate the progressive credentials of a Democrat who, in his Senate campaign, was chiefly criticized for being too progressive and not diluting his positions to account for the state’s conservative tint. They point to his support for Medicare for All and for leftist drug, military and immigration policies. And they were buoyed by the release of a straw poll by the progressive advocacy group MoveOn this week that put O’Rourke first in a field of potential 2020 candidates.

In response to a constituent on Friday, O’Rourke reiterated his support for background checks and a ban on the sale of assault-style weapons. And he pushed back against criticism that he took money from employees of oil companies in a race in which he raised more than $70 million from a national network of mostly small donors.

He said it is “really important to remember we did not receive a single PAC contribution” and that the campaign took money from employees of a range of industries, including the “cosmetology industry, the telecommunications industry, the cupcake baking industry.”

“We received more contributions than any Senate candidate in the history of the United States of America, so we were No. 1, No. 2, No. 3 for almost every industry,” he said.

“I am who I am,” he said. “I laid out my vision for Texas and this country over the last two years without taking a single poll to find out where people were on the issues or how popular it was or how it would track in this community or that — said the same thing in Amarillo that I said in Houston, Texas, so I mean, go figure.”

During a Senate campaign that captivated the Democratic Party and elevated his national profile, O’Rourke largely avoided criticism from fellow Democrats. But unlike in the Texas Senate race, where O’Rourke benefitted from running against a Republican foil, Ted Cruz, Democrats in the presidential primary will have other choices. Top-tier progressive contenders such as Sens. Bernie Sanders (I-Vt.) and Elizabeth Warren (D-Mass.) have been courting activists and donors for months.

In an early test for O’Rourke in the “ideas primary” at the front end of the presidential campaign, progressives writing in Current Affairs and The Washington Post, respectively, called him “plainly uninspiring” and said he “rarely challenged concentrated power in D.C.”

A headline in the socialist Jacobin magazine went even further: “We don’t need another photogenic media star with run-of-the-mill liberal politics running for president.”

Among other criticisms, progressives have faulted O’Rourke for his 2015 vote granting then-President Barack Obama “fast track” trade promotion authority for a controversial Asia-Pacific trade agreement, and for not joining the Congressional Progressive Caucus.

Asked Friday why he did not join the caucus, O’Rourke said, “I don’t know that it was much of a conscious decision.” In retrospect, he said, he said he would advise House members not to join any caucus.

“Don’t join any of the caucuses,” he said. “Just be there and be open to working with and getting stuff done with anyone.”

O’Rourke’s allies here have met the criticism from progressive activists with incredulity. Veronica Escobar, the Democrat elected to succeed O’Rourke in the House, told POLITICO that “the proof is in the pudding.”

“I see him as a progressive Democrat,” she said.

Still, Escobar worries about the inclination of Democrats to place litmus tests on one another in a presidential campaign. She said, “We have to remember the commonalities before we’re too quick to tear each other apart for our differences.”

O’Rourke himself kept his focus squarely on President Donald Trump, and on the significance of the 2020 general election, not the Democratic primary.

“Whoever is running may very well be running against somebody who has not the slightest respect for our norms, our traditions, our institutions, civility, dignity, decency in public life,” he said. “This is the mother of all tests for this democracy, and whether we can run a campaign — have candidates at all levels, from school board to the White House — who are willing to focus on issues, on our potential, on our promise, on the future, instead of our fears, instead of attacking one another personally.”

He said, “I know that something good is going to come out of all this at the end of the day. But there’s never been a darker moment, at least in my lifetime, in this country.”

O’Rourke’s town hall — and border visits planned for later Friday and Saturday — come just days after a fellow Texan, Julián Castro, announced that he is forming an exploratory committee ahead of a likely run for president. But speculation surrounding O’Rourke has overshadowed the early Democratic field.

In El Paso on Friday, constituents packed into a high school auditorium cheered when a former field organizer for his Senate campaign said to O’Rourke, “Hate to see you go, but you’re going to run for president, right?”

O’Rourke took a sip of water from a bottle and only smiled.

“It’s now five-plus weeks from the election,” he told reporters later, and “I’m no closer to deciding.”

He said he has “no hard date” on making a decision about entering the race.