AUSTIN -- A liberal Texas political group has filed a formal complaint alleging that a recent fundraising solicitation mailed by U.S. Sen. Ted Cruz's presidential campaign violated state law.

The solicitation came in an envelope featuring a return address in official government type and the words "check enclosed." The "check" was a fake check made out to Cruz's campaign, accompanied by a missive asking the recipient to send in a "matching donation."

Such fundraising techniques are relatively common, but in Texas they may now be illegal under a law passed last year by the state Legislature.

The law, House Bill 1265, authored by Houston Democrat Gene Wu, required solicitations resembling government notices, checks or negotiable invoices to include, "in at least 18-point type," the words "SPECIMEN-NON-NEGOTIABLE."

Cruz's mailer said -- in small type -- "this check is a facsimile not redeemable or negotiable and has no cash value."

The liberal group, Progress Texas, filed the complaint Monday with the Attorney General's Office, according to a copy obtained by the Houston Chronicle.

"This is the kind of mail my legislation was trying to prevent," Wu said in a statement about the complaint. "It certainly breaks the spirit of the law, and I agree that the Texas' Consumer Protection Division should look into whether or not it breaks the letter of the law, as well."

A Cruz spokeswoman did not immediately return a message seeking comment about the complaint. The campaign has defended the mailer from criticism on Facebook and elsewhere by noting that "match-type fundraising mailers are common to both campaign and non-profit solicitations."

The critics on Facebook included Darrell Maloney, a Lubbock man who posted that his 83-year-old mother had confused the mailer for a Social Security check.

The latest dust-up comes just about a week after Cruz fought off criticism over a mailer sent to Iowa voters that accused recipients of "voter violations." That mailer showed percentages that supposedly represented how often the recipients and their neighbors had gone to the polls and threatened that another notice would be sent to the neighborhood after the caucuses.

Cruz's campaign also was criticized for telling supporters on the night of the caucuses that they should tell other caucus-goers that neurosurgeon Ben Carson was likely to drop out of the race. CNN had reported that Carson was leaving the campaign trail, but not that he was dropping out.

Cruz apologized for that incident.