DALLAS — Sen. Don Huffines made a six-figure donation to a shadowy nonprofit weeks before it trashed fellow Republican and Senate hopeful Angela Paxton.

Huffines, R-Dallas, gave the American Liberty Network $150,000 in January, the only donation from a politician it received all year, according to ethics filings. Soon after, the group's Texas chapter sent mailers and made robocalls attacking Paxton and her husband, Attorney General Ken Paxton.

At the time, Angela Paxton was locked in a brutal Republican primary race for the Senate District 8 seat with Huffines' twin brother, Phillip. Despite these attacks and the $8.4 million that Phillip Huffines spent, Angela Paxton won the party's nomination with 54.4 percent of the vote.

Phillip Huffines has insisted that his campaign was not involved in the attacks, and his consultant Matt Langston declined to comment this week.

Ethics experts say the American Liberty Network, a 501c(4) "dark money" group, could have violated state campaign finance rules by not disclosing its involvement in the race.

‘Just a donation’

The attack ads targeted both Paxtons, who are popular in GOP circles, especially in North Texas. Ken Paxton first won elective office during a Republican surge in 2002, and Angela Paxton is well-known in staunchly conservative women’s groups such as the Plano-based Golden Corridor Republican Women’s Club.

Despite these conservative credentials, the mailers contended that Angela Paxton was a “RINO,” a Republican in Name Only, and criticized her husband for his legal troubles.

"Angela Paxton's husband is currently under felony indictment for criminal fraud charges," the mailers read, according to a copy published by the conservative advocacy group Empower Texans. "Through scandals, investigations and unethical behavior, the Paxtons have been plagued by problems that we would hope citizen representatives would avoid."

The mailers then attempted to convince voters that Phillip Huffines was more conservative.

"Will you oppose all tax and fee increases and cut taxes and spending instead?" the mailer asked, next to pictures of Phillip Huffines and Angela Paxton. There's a check mark next to Huffines' picture.

At the time, Phillip Huffines condemned the mailers and robocalls.

"Let me be clear," he tweeted on March 1. "This is not from our campaign, and we condemn any and all such attacks."

Angela Paxton's campaign did not respond to a request for comment for this story. But Anthony Holm, her spokesman then, did not buy Huffines' defense, telling Empower Texans in March: "This deceitful behavior falls squarely on the shoulders of Phillip Huffines.

"This is yet another example of a group with conspicuous ties to Phillip Huffines which is either advancing falsehoods or, in this instance, violating the law and advancing falsehoods."

1 / 3Senate candidates Phillip Huffines and Angela Paxton shook hands after a Republican Club legislative forum in Fairview on Jan. 8.(Jason Janik / Special Contributor) 2 / 3Candidates Phillip Huffines, left, and Angela Paxton discuss their policies during a Republican Club legislative forum at Heritage Ranch Golf and Country Club in Fairwiew, TX, on Jan. 8, 2018. (Jason Janik / Special Contributor) 3 / 3These campaign signs are along Custer Road for Texas Senate candidates Phillip Huffines and Angela Paxton. They were seeking the Republican nomination in the March 6, 2018 primary.(Valerie Wigglesworth / Staff)

Don Huffines did not weigh in on the attacks then, nor did he say publicly that he had made a huge donation to the group behind them.

Huffines' donation to the American Liberty Network was the single largest expenditure his campaign has made this year, according to the senator's last financial report. His next-biggest cost was a $100,000 contribution to his brother's campaign, made the day after his donation to the American Liberty Network.

It’s unclear whether the group received any other money this election cycle. The Huffines donation was the only one made to the American Liberty Network or its affiliates that was disclosed by a candidate or elected official.

The network has not yet filed federal tax forms and won’t have to for months. As a 501(c)4, the group may be politically active as long as that’s not its primary purpose. The IRS does not require these so-called dark money groups to disclose their donors.

A note on the network's website says, "Donations, contributions and gifts to AMERICAN LIBERTY NETWORK are not refundable."

'So darn easy to comply'

Unless Sen. Huffines coordinated with the American Liberty Network to send the attack mailers, it’s unlikely he violated any campaign finance laws, experts said. But these same experts said the group may have broken a campaign finance rule that requires dark money groups to disclose political communications.

The Colorado-based network, which operates here under the names Texas Liberty Alliance LLC and Texas Liberty Network, was incorporated in Virginia last October.

On its website, the network describes itself as “a non-profit organization committed to educating the citizens and politicians about the Constitution, and how public policy affects their Constitutional rights of all Americans.”

But Lucius O'Dell, Zach Lautenschlager and Nathan Barnes, the three directors named on the group's Virginia incorporation documents, have been active for years in politics in Texas and other states, and all have connections to the National Association for Gun Rights.

NAGR has given thousands of dollars to Texas House and Senate candidates since 2014. Many of its contributions went to members of the Texas House Freedom Caucus, but Phillip Huffines has received the most from the NAGR’s political action committee, which donated $5,000 to his campaign in December.

The American Liberty Network and Texas Liberty Alliance, described online as "a state chapter" of the network, are brand new. In fact, the latter was not registered with the Texas secretary of state until April, the month after the primary.

State rules require groups to notify the Texas Ethics Commission within 30 days of an election if they make political communications that are “susceptible to no other reasonable interpretation than to urge the passage or defeat of a candidate or ballot measure.”

The mailers and robocalls were made in late February and early March, Empower Texans said, just days before the March 6 primary.

Jim Clancy, a Corpus Christi lawyer who served on the Ethics Commission, said the group should have disclosed the mailers as a “direct political expenditure.”

"What you described sounds like a campaign communication to me," Clancy told The News. "If it is a campaign communication, then that direct expenditure needs to be disclosed."

The group could face up to a $5,000 fine if a Texas resident files a credible complaint with the commission. If that doesn’t happen, the American Liberty Network and its affiliates are unlikely to face any consequences.

“I mean, come on,” Clancy said. “The rule is so darn easy to comply with.”

David Keating, an expert with the Virginia-based Institute of Free Speech, said he thinks the American Liberty Network’s mailer walked close to — but may not have crossed — the line.

“When you get into character, that gets into fitness for office. Doing that is risky,” Keating said. “They get pretty close to the line. But I wouldn’t sit here and say they definitely went over it.”

Barnes, Lautenschlager and O’Dell did not respond to requests for comment. Calls and emails to the American Liberty Network and Texas Liberty Network went unreturned.

Don Huffines, who represents Dallas in the state senate, is running for re-election this year against Democrat Nathan Johnson. Election Day is November 6.