RICHARDSON, Texas — Sweat is beading on Deval Patrick’s brow. The midday Texas sun pushes the temperature to 98 degrees. But volunteers who gathered at the congressional campaign office that he’s dropped by in this Dallas suburb are lining up for photos.

He takes a final five pictures. Then two extra, final, final pictures. Then he hugs someone. Then he shakes a few hands.

When he finally slides into his air-conditioned sedan, an Enterprise rental, one person yells out that he’d make a good president.

“Easy now,’’ Patrick says with a chuckle. “Easy now.’’

Patrick isn’t running for anything. At least not yet. But the former Massachusetts governor spent this July weekend in the dry Texas heat to see how it might feel to join the ever-growing field of Democrats who are jockeying for the 2020 nomination.

He was ostensibly here on Sunday to buck up volunteers for Colin Allred, the former Tennessee Titans linebacker who is trying to unseat Representative Pete Sessions, a Republican in one of the most closely watched House districts in the country. It was a quick stop on his way to San Antonio, where Patrick gave a keynote speech during a lunch at the NAACP convention on Monday. He was the only potential 2020 candidate to do so.

This swing through Texas gives Patrick a chance to try out his message of hope and unity and to see if it strikes a chord amid a rancorous political moment in which partisan attacks and arguments reign. It is also to determine whether he’s got the stamina and the desire to spend the next two-plus years traveling the byways of the nation and traversing airports, contending with security hold-ups and flight delays on the path to a Democratic nomination for president.

“It’s about figuring out what role I can play in the party and in politics, now and the future,’’ Patrick said in an interview in Richardson on Sunday. “I don’t think the most successful political strategy for Democrats is simply to perfect our critique of Republicans. I think we have to offer a positive alternative.’’

The 2020 Democratic field is expected to be as wide as an Iowa corn farm — unlike last time when Hillary Clinton was the presumptive nominee three years before she clinched the spot. Other potential contenders already include US Senators Elizabeth Warren, Cory Booker, Kamala Harris, Bernie Sanders, and former vice president Joe Biden. Democratic strategists believe there could eventually be three dozen candidates making trips to Iowa and New Hampshire to try their chances to take on President Trump.

The top tier of Democratic candidates has been quietly working for a while. While this was Patrick’s first foray into the 2018 congressional contests, Warren has raised $15 million for Democrats since 2013. She’s donated $5,000 to each of the 50 state parties, plowed money into congressional races and national party committees and also supported efforts to reform the process of redistricting. Since Trump was elected, she’s been to Ohio, Wisconsin, Minnesota, Michigan, Washington, Texas, California, and Nevada — in addition to running for reelection in Massachusetts.

She’s even helped raise money for Allred.

Patrick, who turns 62 this month, offered on Monday a taste of what his message might be in a 40-minute speech that combined partisan digs with an overarching theme intended to reclaim notions of American exceptionalism.

“I don’t know when patriotism in our country got reduced to lapel pins and flyovers and questions about whether pro football players should or should not take a knee,’’ Patrick said at the NAACP convention. “Surely it’s more than that. I think patriotism has something to do with really understanding what makes this nation great.’’

Patrick is considered one of the best orators in the Democratic Party, someone Barack Obama looked to for inspirational lines.

His message was a contrast to the sort of counter-punching, anti-Trump rhetoric that other Democrats have come to employ. He never mentioned the president by name.

And some of his biggest applause lines came when he asked the crowd to help improve the national political discourse.

“We’ve come to whisper kindness and to shout anger,’’ Patrick said. “I don’t know if that comes from the reality-TV culture we live in or what. But I do know that it’s upside down. It’s time we learned to shout kindness, to shout justice, and to shout compassion.’’

One woman in the audience said later that she wants the phrase “shout kindness’’ on a T-shirt.

The NAACP is a nonpartisan organization, but the Trump administration didn’t send anyone to its convention this year. The president skipped it last year, sending Deputy Attorney General Rod Rosenstein in his stead.

Some talk of 2020 swirled in the convention center Monday. NAACP chairman Leon W. Russell spoke shortly before Patrick and implored the lunch audience to listen to him closely.

“You might look at Deval Patrick as the kind of person you would consider,’’ said Russell. “Whether it be for governor, or senator. Whether it be for president of the United States.’’

The crowd clapped.

Patrick left office in Massachusetts in 2015 — after a eight years as governor. He hasn’t campaigned for himself since his 2010 reelection, and when he spoke to a small crowd on Sunday, he asked them to bear with him because he is rusty.

“I’m a little out of the speech-making business,’’ he admitted to a roomful of about 50 volunteers. “I’m out of practice, but you all inspire me.’’

Six minutes into his pep talk he used a line familiar to Massachusetts audiences and implored the audience to “turn to each other, not on each other.’’

The group was entranced, and one woman whispered: “He’s good.’’

He chit-chatted with the volunteers, often putting his right hand to his chin as he leaned in to hear them. He wore sneakers, khaki pants and a light blue button-down. He held a baseball cap emblazoned with “Sweet P,’’ the name of his Western Massachusetts farm.

He joked about grandchildren. “If you had known they were that good, you would have skipped the kids!’’

One of the key questions Patrick will have to contend with should he run is how his corporate resume will be viewed by the base of the party. Patrick introduced himself as “a former civil rights lawyer, a business executive’’ but didn’t mention the name “Bain Capital,’’ where he currently works. First led by Mitt Romney, the venture capital company was pilloried by Democrats during the 2012 presidential election.

And in an interview, Patrick made it clear that he remains dedicated to his position as a managing director there. “I have a great business and a terrific team,’’ said Patrick. “Investments that are important to us and important to the companies we’ve invested in and important to the field of impact investing.’’

His involvement in 2018 midterms, he said, comes from his worry about the direction of the country, but he is not in a position to do it full time right now.

Or, as Patrick put it: “I’m trying to be engaged when I can, consistent with my day job.’’

Annie Linskey can be reached at annie.linskey@globe.com.