HOUSTON — In a raucous swing Sunday through a state long starved for Democratic presidential attention, U.S. Sen. Bernie Sanders rallied thousands of people with a progressive clarion call that urged his adopted party not to neglect deeply Republican Texas.

"One of the problems that exists in American politics today, in my view, is that the Democratic Party has conceded half of the states in the country at the national level, and that's wrong," Sanders, a Vermont Independent running as a Democrat, said during a rally at a downtown Dallas hotel.

Several hours later at a similar event in Houston, he sharpened his advice for Democrats, saying the "simple truth is that you cannot be a national political party which claims to represent working families and low-income people and turn your back on some of the poorest states in America."

"If we are serious about change in America, we can't just do it in blue states," he declared earlier in Dallas, emphasizing the need for a "50-state strategy" that leaves no voter in the dark.

Yet Sanders' Texas talk came with a hint of optimism as he raised the prospect of the end of Republican dominance in the state. It was a reliable applause line in Dallas and Houston, cities in the heart of counties critical to Democrats' hopes for a bluer Texas.

“I am here to tell you that today this is a conservative Republican state, but that doesn’t mean it will be conservative Republican tomorrow," Sanders said after taking the stage in Houston, remarking he did not want to become dizzied by the stadium-style crowd. "And with the energy I see in this room, it may be sooner than tomorrow."

Sanders' daylong trip to Texas easily represented the most well-attended visit to the state by any presidential candidate so far this election cycle. His campaign said 8,000 people turned out in Dallas, while 5,200 showed up in Houston.

At each stop, Sanders railed against a "billionaire class" and called for a "political revolution" while pitching a host of proposals on liberals' wish lists. He touted his support, often in conjunction with shots at his Republican rivals, for a $15 minimum wage, a massive federal jobs program, free tuition for public colleges and universities, a single-payer health care system, a pathway to citizenship for people in the country illegally and campaign finance reform including a rollback of the U.S. Supreme Court's Citizens United decision. Acknowledging some of his plans would be pricey, Sanders assured supporters that the wealthiest members of society would foot the bill with high taxes.

Sanders blended into his stump speech ample nods to Texas, specifically calling out the state's GOP leaders for overseeing high levels of people without health insurance and unemployment in some quarters of the economy. Discussing the need for energy alternatives in Dallas, he acknowledged many Texans rely on the oil industry for a steady job, and they would have to be protected if the economy shifted toward another source.

However, no reference to Texas drew longer and louder applause than when Sanders mentioned Sandra Bland, a young black woman found dead last week in a jail cell in Waller County, about an hour north of Houston. Sanders, who was interrupted at a forumSaturday in Phoenix by activists angered by police brutality, brought up Bland while listing other African Americans who have recently died in police custody.

“It is unacceptable that police officers beat up people or kill people," Sanders said in Houston. "If they do that, they have got to be held accountable.”

Sanders has emerged as the most popular alternative to Democratic front-runner Hillary Clinton, drawing massive crowds and creeping up in the polls while remaining an unmistakable underdog. Clinton, the former secretary of state, has visited Texas once since announcing her candidacy, a swing that included one public event in the form of a major speech on voting rights in Houston.

"Obviously Hillary Clinton is the general favorite — she's far out in the polls and she speaks" well about the top issues for Democrats, said Lane Lewis, chairman of the Harris County Democratic Party. "Bernie, however, is certainly making a splash in the pond. It seems like everywhere he goes his crowds get bigger and bigger."

It was not Sanders' first visit to Texas since presidential buzz began surrounding him. In a comparatively low-key trip, he dropped in on Austin in April to meet with union workers and headline a fundraiser for the Travis County Democratic Party.

Andrew Andrews, a mail courier from Hurst who came to see Sanders in Dallas, welcomed the senator's emphasis on stumping across the "entire country and not just the strongholds" for Democrats.

"To see him come down here, which most Democratic candidates write off — it's refreshing," Andrews said. "We don't really get to hear a lot of people like that down here in Texas."