By Suzanne Gamboa

Rep. Joaquín Castro, D-Texas, the twin brother of presidential candidate Julián Castro, may run for the Senate next year, his political adviser said Friday.

Joaquín Castro’s Senate prospects have been getting some buzz after former Rep. Beto O’Rourke of Texas said he was not interested in taking on the state’s senior senator, Republican John Cornyn, in 2020. O'Rourke ran a competitive if unsuccessful race last year against Sen. Ted Cruz, R-Texas, and is considering a presidential run himself.

“Joaquín will seriously consider running for Senate in 2020,” the adviser, Matthew Jones, said in a statement.

For now, the congressman, who chairs the Congressional Hispanic Caucus, is focused on “protecting Texans — and all Americans — from the most consequential challenge to our constitutional separation of powers that we have seen in a generation,” Jones said.

Joaquín Castro was the sponsor of a resolution that easily passed the house to block the national emergency declaration President Donald Trump issued after Congress refused to provide billions of dollars to build a border wall.

“He will not stand by while the president attempts to unilaterally strip Texans of their land to build a wall in a manner that most Americans, especially Texans, disagree with,” Jones said.

A Senate vote on Castro’s resolution is expected to be close. Cornyn has said he’ll vote against he House measure. Trump has said he'll veto it.

Julián Castro, a former U.S. housing secretary, told The Associated Press on Thursday that his brother would beat Cornyn, who was elected in 2002 and is seeking his fourth term. "My brother would win,” Julián Castro said.

“There are a lot of Texans that clearly have problems with the way that he has represented the state,” Julián Castro said of Cornyn. “Most recently, refusing to stand up to Trump even though a lot of land is going to get taken, a lot of Texas landowners’ property is going to get taken if there is a wall.”

Cornyn had been sending fundraising solicitations based on the prospect that O’Rourke might challenge him.

Sen. John Cornyn, R-Texas, address a crowd at a rally for President Donald Trump at the El Paso County Coliseum on Feb. 11, 2019, in El Paso, Texas.Eric Gay / AP file

A recent Qunnipiac poll put Cornyn’s approval rating at 43 percent. In addition, another quarter of Texans disapprove of Cornyn’s performance, giving him a net approval of +17, NBC’s First Read reported.

The poll found that Texas voters are evenly split, 48 percent to 48 percent, on whether to build a wall on the border. At the same time, they disapprove by a large margin — 60 percent to 39 percent — of Trump using emergency powers to pay for it.

Texas voters strongly opposed the seizing of private property by the federal government to build the wall, 62 percent to 33 percent.

But with his many years in office, Cornyn has a hefty campaign chest. He had $6 million on hand at the end of January, his campaign reported.

While O’Rourke’s decision to pass on the Senate race opens a path for Joaquín Castro, it could put O'Rourke square in the path of fellow Texan Julián Castro should O’Rourke run for president.

Of course, Castro already is facing a crowded field, and O'Rourke would, too.

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