Deep in the heart of Texas, a billboard truck will soon hit the road with a curated list of President Donald Trump's tweets — attacks on Sen. Ted Cruz, a former political foe.

Trump popularized the term "Lyin' Ted" in 2016. But it's 2018 now, and Democratic voter mobilization and an unlikely challenger have mounted an improbable campaign for a reliably Republican seat.

Trump said an October rally is in the works to lend Cruz support. "I'm picking the biggest stadium in Texas we can find," Trump said Friday on Twitter.

"Help from the president was long unthinkable in a race that for months looked like a Cruz cakewalk," the Associated Press reported.

Antonio Arellano, a Houston-based activist and Latino community organizer, thought fellow Texans may need a reminder of how Trump has suggested they vote when Cruz is on the ballot. He was already in the market for a billboard when he tweeted a doctored image carrying a real Trump tweet from 2016.

"Why would the people the people of Texas support Ted Cruz when he was accomplished absolutely nothing for them. He is another all talk, no action pol!" the tweet read.

His project became more possible, Arellano said Sunday, with each retweet and suggestion that it could be fully realized.

"My followers were saying, 'Where can I donate? Let's make this happen,' " he told the Washington Post.

He started a GoFundMe page to fuel the effort, and donations soared. Arellano was subsequently joined by David Hogg, a former student at Marjory Stoneman Douglas High School in Parkland, Florida, who got involved after catching wind of the image on Twitter. Political activist Claude Taylor also joined the effort, and their $6,000 goal was met and surpassed within a day, Arellano said. The group raised $9,760, then turned away further donations, he said. He hopes to have the truck on the road in the next two weeks.

Arellano said the actual billboard will be a mobile truck with two sides, and could carry two different tweets at once, one on each side. The route has not yet been planned, but Arellano said he is exploring where in the state he should dispatch it with the hashtag #TrumpTweetTruck.

The Cruz campaign did not immediately respond to a request for comment.

The billboard seeks in part to highlight the contentious history between Cruz and Trump at a moment when they need each other, although Arellano said it mostly criticizes Cruz for not challenging Trump's hard-line immigration policies that have affected Latinos in Texas. Cruz's father is a Cuban immigrant.

Trump is supporting Cruz in a tighter-than-expected race to keep a Republican majority in the Senate. Cruz seeks to fend off Democratic Rep. Beto O'Rourke, who is riding a wave of national coverage. Although he would be the most serious Democratic contender to unseat a Republican in years, O'Rourke's path to victory would be difficult in the comfortably conservative state. Still, a recent NBC News-Marist College poll found O'Rourke trailing Cruz by just four percentage points in a state Trump won by nine, the Washington Post reported.

There are more than a few tweets the truck could highlight. Trump has tweeted he doubts Cruz's Christian bona fides and attacked the physical appearance of Cruz's wife. In response, Cruz called Trump a "sniveling coward."

"It's not easy to tick me off. I don't get angry often. But you mess with my wife, you mess with my kids, that'll do it every time," Cruz said. "Leave Heidi the hell alone."

But Cruz now welcomes Trump's support as O'Rourke draws in potential voters with a message of unity and compassion in a vitriolic political world, and will often avoid naming Cruz and Trump directly.

Trump has trained his Twitter salvo on O'Rourke, calling him a "disaster for Texas" on Friday.