Donald Trump wants to build the wall. A wannabe-Donald Trump in Arizona wants to annex Mexico.

Ahead of a general election where the Grand Canyon State could be a bit of a problem for the president, the wealthy owner of a cosmetics company, Daniel McCarthy, is challenging incumbent Sen. Martha McSally in the Republican primary. His platform? So far it includes annexing Mexico.

“There is a process to become states for the United States,” McCarthy said Tuesday morning on an Arizona radio station. “Clearly 30 million Mexican illegal immigrants want to be United States citizens, probably half the country wants to be United States citizens.”

And so, the aspiring lawmaker from a border state would like the citizens of Mexico to turn their attention to Article IV, Section 3, Clause 1 of the U.S. Constitution. It stipulates that “new states may be admitted by the Congress into this union.”

“I want to speak above the Mexican government. Okay? When you’re talking to the Mexican citizens, ‘Rise up in your communities and petition to become states for the United States.’ That’s how that process works,” he said, before adding that “by the way, it’s not that challenging.”

Consultants, he said, encouraged him to speak to voters north of the Rio Grande before pitching potential citizens south of that river. Andrés Manuel López Obrador, president of Mexico and the leader of the No 1. trading partner with the United States, would probably agree with that approach.

McCarthy has other ideas too. He agreed with the radio host on Tuesday that adding some “beachfront property” to U.S. territory might be nice.

“There’s a reason they’re coming here,” he said of immigrants crossing into this country illegally. “Now listen, we need to have a border wall immediately, and then after that then we can start talking about maybe some solutions.”

McCarthy predicted that he would “get so much hate” for his annexation idea, but the reasoning behind it is sure to stir criticism as well. Mexican citizens should welcome becoming part of the United States, he asserted, because of conditions in their home country. “Listen, you think anybody wants to live like that?” the wannabe senator told the show’s host.

Annexation hasn’t been a winning political idea since the age of American imperialism in the early 20th century, but the McCarthy campaign told RealClearPolitics on Wednesday that the candidate is serious about the proposal, which he sees as an extension of President Trump's America First immigration policy.

Indeed, the Trump administration has flirted with the idea. Albeit, to a much, much smaller degree.

“The Rio Grande, what side of the river are you going to put the wall?” asked then-Interior Secretary Ryan Zinke just three months into a young Trump administration. “We’re not going to put it on our side and cede the river to Mexico. And we’re probably not going to put it in the middle of the river.”

Zinke would later resign amid an ethics investigation, and the implied notion of annexing Mexican territory went nowhere. It could be resurrected if McCarthy keeps the primary competitive against McSally. This, no doubt, would cause Republicans a headache.

Trump carried Arizona, winning its 11 electoral votes, by just 3.5 percentage points. The president has returned to the state twice during his tenure as that slim margin has given Democrats hope for flipping the state in 2020.

Polling released Wednesday by a labor organization shows Trump barely holding off both Elizabeth Warren and Joe Biden. Add to that shifting demographics in Arizona, and it is no longer a safe bet for Republicans to assume Arizona will remain red.

Those warning signs were enough to inspire a Sunday editorial in the conservative News-Herald, the hometown paper of Arizona GOP Chairwoman Kelli Ward.

“It seems that Arizona’s Republican leadership is determined to see the state turn blue in 2020,” the editorial board of the News-Herald grumbled. “It has been disappointing to watch the state GOP bumble along this past year, first with news about anemic fundraising numbers, and more recently with surprisingly tone-deaf statements that have only served to highlight divisions within the party and embolden Arizona Democrats."

Add to that eye-rolling sure to be inspired by McCarthy’s annexation talk.

Trump has already given his full endorsement to McSally, a retired fighter pilot, combat veteran, and staunch administration ally. McCarthy potentially stands in the way of her reelection, another possible headache for Republicans eager to build on their slim Senate majority and keep the White House -- not annex Mexico.