Rep. Joaquin Castro, D-Texas, accompanied by other member of Congress, speaks about a resolution to block President Donald Trump's emergency border security declaration on Capitol Hill, Monday, Feb. 25, 2019 in Washington. House Democrats have introduced a resolution to block the national emergency declaration that President Donald Trump issued last week to fund his long-sought wall along the U.S-Mexico border, setting up a fight that could result in Trump's first-ever veto. (AP Photo/Alex Brandon)

LAS VEGAS - Democratic presidential candidate Julian Castro said Thursday that his twin brother, Rep. Joaquin Castro of Texas, is considering a big run of his own in 2020 — a bid for U.S. Senate against Republican John Cornyn.

"He's considering that, but he really has not made a decision about whether he's going to do that. I would imagine he would make a decision at some point soon," Julian Castro told The Associated Press during a campaign stop in Nevada.

In Texas, no clear rival has yet emerged to take on Cornyn, who until this year was the No. 2 Republican in the Senate before being term-limited out of that leadership role.

Beto O'Rourke's narrow loss to Republican U.S. Sen. Ted Cruz in November breathed new life into long-suffering Texas Democrats, who haven't won a statewide office since 1994. As recently as last week, O'Rourke had suggested he may consider challenging Cornyn, but taking another run at the Senate is looking less likely as he promises to announce a decision soon on a 2020 presidential run .

A spokesman for Joaquin Castro did not immediately comment.

Democrats are searching for a challenger to Cornyn, who has comfortably won re-election since joining the Senate in 2003. So far, no other prominent Texas Democrats have signalled interest.

Joaquin Castro is the campaign chairman of his brother's presidential campaign. But his own profile is also rising in Congress, where he is chairman of the Hispanic Caucus and sponsored a measure passed Tuesday that would stymie President Donald Trump's bid for billions of extra dollars for a U.S.-Mexico border wall.

The resolution would block Trump's national emergency declaration and is now before the Republican-run Senate, where there are enough GOP defections to edge the resolution to the brink of passage. Cornyn has said he will vote against the measure.

"I think he'd beat him. My brother would win," Julian Castro said. "There are a lot of Texans that clearly have problems with the way that he has represented the state. 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's a wall."

The Castros started their political careers around similar times but took different directions. Joaquin Castro made a slow climb to Congress after a decade in the state legislature, while Julian Castro quickly received national attention after being elected San Antonio mayor at age 34.

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Weber reported from Austin, Texas.

News from © The Associated Press, 2019