Rep. Beto O’Rourke (D-Texas) on Friday officially jumped into the race to take on Sen. Ted Cruz Rafael (Ted) Edward CruzSenate Republicans face tough decision on replacing Ginsburg Cruz: Trump should nominate a Supreme Court justice next week Renewed focus on Trump's Supreme Court list after Ginsburg's death MORE (R-Texas) in 2018.

O’Rourke is the first announced Democrat running to unseat Cruz in what will be a steep uphill battle in a reliably red state. The Texas Democrat has been crisscrossing the state over the past four months gauging support for a statewide bid.

He made Friday’s announcement from his hometown of El Paso, which he has represented in Congress since 2013.

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Before he can take on Cruz, O’Rourke will need to win the Democratic primary. Fellow Texas Rep. Joaquin Castro (D), a rising star in the party, is still considering a bid. His political director said he will make a decision "in the coming weeks."

Any Democrat who emerges faces a tough fight to unseat Cruz. No Democrat has won a Senate election in Texas since 1988. And while Cruz has irked those within his party, he's been able to expand his national profile and donor base after unsuccessfully running for the GOP presidential nomination.

As O’Rourke entered the race, he quickly garnered an endorsement from a national progressive group. The Progressive Change Campaign Committee (PCCC) sent out a fundraising email to its 1 million members nationwide and nearly 50,000 in Texas in support of O’Rourke.

Cruz also fundraised off the announcement, saying that O’Rourke will have the support “of the mainstream media and a Washington establishment willing to do everything in their power to see Ted Cruz defeated.”

But Texas Democrats running for the Senate won’t likely be able to count on financial help from national Democrats. The party has a tough Senate map in 2018, with 10 incumbents up for reelection in states carried by President Trump in the 2016 election.