HOUSTON - In the final weeks to Election Day, US Vice President and Democratic presidential nominee Kamala Harris is to make a surprise visit to Houston, Texas, on Friday, as the Senate race between Democratic Congressman Colin Allred and Republican Senator Ted Cruz has become more competitive in the largest red state.

This marks Harris' first stop in Texas since July, where she will appear with Allred at a Friday afternoon rally, reportedly focusing on abortion rights, an issue central to elections nationwide.

Allred, a three-term US representative from Dallas, has been narrowing the polling gap with Cruz and consistently outraising him. National Democratic groups have poured millions of dollars into Allred's campaign.

Cruz, who is seeking for his third term, is still favored to win with an average lead of about four percentage points in recent public polls. However, two leading election forecasters now shifted the race from "likely Republican" to "lean Republican".

On Sunday, the Dallas Morning News, the state's top newspaper by daily circulation, endorsed Allred, dealing another setback to Cruz. Some Democrats now view Texas as one of their best opportunities to gain a Senate seat.

Allred has centered his campaign on Texas' abortion ban, one of the strictest in the country, blasting Cruz for supporting a law with no exceptions for rape, incest, or the life of the mother. He also slammed Cruz for "only focused on himself", citing the two-term senator's 2021 Cancun vacation when millions of Texans lost power for days in a deadly historic winter storm.

Cruz, on the other hand, has leaned heavily into immigration issues, accusing Allred and Harris of repeatedly voting for "open borders", while largely avoiding addressing abortion exceptions, deferring the issue to state control.

Harris County, which includes much of Houston, is a Democratic stronghold. In 2020, Biden won the county by 13 points, but Trump carried Texas by 5.6 points. Texas has remained the largest red state since Jimmy Carter's victory in 1976.

Early voting began across Texas on Monday.