(CNN) - Sen. Ted Cruz's reelection campaign on Tuesday defended a mailer labeled as "Official Travis County Summons" that was soliciting campaign contributions.
The Texas Republican's campaign had faced criticism for the mailer after it was shared on social media.
Sean Owen, a resident of Austin, Texas, tweeted, "Received this for my 88-year-old grandma. Says it's a summons from Travis County, but is actually asking for money for @tedcruz. Did your campaign authorize this? Is this even legal? Shame on you. That's one more @BetoORourke voter."
The image was retweeted over 34,000 times as of Tuesday afternoon.
But the Cruz campaign denied in a statement that the mailer was misleading to voters.
"Out of millions of fundraising mailers targeting people who give to Republicans -- clearly labeled on the front with 'Ted Cruz for Senate' -- there were a few complaints that came not to us but through the local media or twitter," a campaign spokesperson said. "Our mail efforts have been both effective and critical to identifying and engaging our supporters, and getting them involved in our campaign efforts to keep Texas strong."
And a senior Cruz campaign aide echoed that pushback, telling CNN that the campaign had sent "millions of these mailers across the state over the last two years," and that "no one has raised an eyebrow until someone who doesn't support Ted (Cruz) tweets about it."
The aide said that the mailers are "targeted to people who have donated to us or to Republicans in the past," and that "it's been done in the past without controversy." The aide also stressed that the mailers were in line with Federal Election Commission regulations.
The campaign of Democratic Rep. Beto O'Rourke, who is mounting an insurgent challenge to the first-term senator, declined to comment on the mailer.
Brendan Fischer, the federal reform program director with the Campaign Legal Center, told CNN that while the mailer likely didn't violate federal law, it was "misleading."
"There's not anything that would prohibit the Cruz campaign from making misleading statements or packaging campaign materials in a misleading envelope, as long as there is a legally required disclaimer on the message," Fischer said. "So, the main requirement for the campaign is that its communications include a disclaimer stating that the Cruz campaign paid for it."
Texas state Democratic Rep. Gene Wu, however, argued that the Cruz mailer could run afoul of Texas state law. Wu wrote on Twitter that the mailers were a "violation of the Texas Deceptive Trade Practices Act (DTPA). I know, because I passed this law in 2015." Violation of that state law could warrant a fine.
But Wu also suggested that the mailer "may actually be criminal," citing state law governing the issuing of summonses, noting that "prosecution of criminal statues is up to your local County Attorney and District Attorney."
Asked specifically about state law, the Cruz campaign aide maintained the campaign "believe(s) we are in full compliance legally."
Reached for comment about potential enforcement action, the Travis County district attorney's office told CNN in a statement that "we have received a complaint; however, it is our policy not to discuss matters related to an ongoing election."
It's not the first time Cruz has faces criticism for his campaign mailers. The senator was similarly criticized during his 2016 presidential bid, when his campaign sent out a mailer to Iowa voters that was labeled "voter violation[s]" in an attempt to drive up turnout.
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