Texas Democratic lawmakers are racking up significant expenses along with the threat of state bribery charges as they continue their high-profile walkout, designed to block a Republican-led redistricting plan supported by President Trump. 

The prolonged absence of the lawmakers, who fled to Illinois and Massachusetts to deny Republicans the quorum necessary for legislative business, has become a costly endeavor for the poorly paid legislators, who are receiving donations and support from key Democratic allies.

Democratic lawmaker Gene Wu, a state House leader, told the Associated Press that the group has encountered expenses ranging from hotel accommodations and meals to logistical support for their continued operations out of state. He said his campaign account paid for the purchase of a microphone for news conferences, while the Democratic Caucus has backed major costs such as lodging for the group of about 50 legislators.

Keeping the group out of Texas for weeks, or potentially months, is expected to take an even higher financial toll. Mr. Wu acknowledged that “a lot of small-dollar donations” are sustaining the effort, adding, “That’s going to be used to help keep this thing going.”

Still, the financial strain is growing. Not only are the lawmakers paying hefty out-of-state lodging and dining bills, but under House rules, they face a potential $500 fine for each day they are absent. The fines, which cannot be paid from office budgets or political donations, dwarf the lawmakers’ monthly legislative salary of $600.

State Senator José Menéndez highlighted the financial burden during a rally in Boston, saying the daily fine nearly equals the lawmakers’ entire monthly salary. “They need your prayers, they need your thoughts, and they need you to get behind them,” he said.

Governor Gregg Abbott says there’s far more than prayers being offered to the missing Democrats. In an emergency petition with the Texas Supreme Court on Tuesday, the Republican governor said Mr. Wu “boarded a chartered plane for Chicago, Illinois, apparently provided as a benefit to withhold their vote and deny a quorum in the Legislature and fled the State with many of the other members of the House Democratic Caucus.”

“That plane, it turns out, was ‘a 76-seat private jet’ taking Wu and other Democrats from Austin to Chicago on ‘a flight that likely cost tens of thousands of dollars,'” Mr. Abbott wrote. “A recent report indicates that the ‘initial amount to get [Wu] off the ground’ was provided by Beto O’Rourke’s political action committee. In addition to offering the initial dollars, O’Rourke’s PAC also offered extensive public relations resources and a dedication of all donations received by the PAC to Wu and other Democrats — but only if they broke quorum.”

Mr. O’Rourke’s PAC, Powered by People, has been a key backer of the wayward Democrats. Though the group has not disclosed the total amount of financial support provided, its spokesman confirmed that Powered by People supplied the Democratic Caucus with the funds needed to cover up-front costs. 

Mr. O’Rourke, a former Texas congressman and Democratic gubernatorial candidate,  himself has hosted events in several states to rally support for the Texas Democrats and encourage further donations.

Texas Attorney General Ken Paxton has launched an investigation into Mr. O’Rourke’s  organization, including “potentially operating an illegal financial influence scheme to bribe runaway Democrats who fled Texas to break quorum.”

“Any Democrat coward breaking the law by taking a Beto Bribe will be held accountable,” Mr. Paxton said in a statement. “Texas cannot be bought. I look forward to thoroughly reviewing all of the documents and communications obtained throughout this investigation. These jet-setting runaways have already lost public trust by abandoning our state, and Texans deserve to know if they received illegal bribes to do it.” 

On Friday, a Texas district judge ruling temporarily prohibited Mr. O’Rourke’s political group from raising funds to support the Democratic lawmakers who left the state. “The group’s fundraising efforts are unlawful and harm Texas consumers,” the judge said.

Mr. Paxton reveled in the ruling. “The Beto Bribe buyouts that were bankrolling the runaway Democrats have been officially stopped,” he said in a statement. “Today, I stopped his deceptive financial influence scheme that attempted to deceive donors and subvert our constitutional process. They told me to ‘come and take it,’ so I did.”

In his defense, Mr. Wu pointed out that financial assistance has been complemented by other forms of support, such as publicity coordination and logistical aid. For example, the Agave Democratic Infrastructure Fund, a Texas-based fundraising and organizing group, has played an instrumental role in helping the lawmakers sustain their efforts, the AP reported.

The Democrats aim to run out the clock on this session of the Texas legislature, set to end August 19, but Mr. Abbott has indicated he will immediately call another special session if necessary. 

Some of the lawmakers say they are willing to suffer the financial burden to get what they want. State Representative James Talarico said the walkout must be sustained by regular people, not wealthy backers, to remain true to its purpose.

“We’ve already been inundated with donations from across the state of Texas, from across the country, just regular people donating $5, $10, $15,” he told the AP. “And that’s appropriate because this fight is for the people, and it should be funded by the people.”