After Ms. Jones won the Democratic nomination for the seat, she and Mr. O’Rourke had a cordial conversation by telephone. Mr. O’Rourke neither pledged to help Ms. Jones nor told her directly that he would be withholding his support, according to people briefed on the call.
In late June, Ronald Smith, a liberal activist in Mr. Hurd’s district, emailed Mr. O’Rourke’s campaign demanding to know: “Has Beto endorsed Gina Ortiz Jones? If not, when will he endorse her?” Mr. Smith said he wanted “a team player for my next Democratic senator.”
An O’Rourke campaign representative offered a noncommittal reply in an email reviewed by The New York Times: “We are evaluating some local and regional races at this time.”
By the summer, aides to Mr. O’Rourke had made clear to Ms. Jones’s campaign that he would not support her candidacy, three Democrats familiar with the exchange said. Mr. O’Rourke valued his relationship with Mr. Hurd and was mentioning it frequently on the campaign trail, as he sought to win crossover support from right-of-center voters.
Ms. Jones, who has said she is likely to run again in 2020, declined through an aide to be interviewed about Mr. O’Rourke.
Mr. O’Rourke’s defenders note that several Democrats benefited from his stronger-than-expected showing against Mr. Cruz, helping the party flip congressional seats in the Houston and Dallas areas.
But in no other swing district was Mr. O’Rourke’s allegiance in question. Mr. O’Rourke carried the 23rd District even as Mr. Hurd narrowly won re-election there. In the section of the district that spills into Bexar County, home to San Antonio, Mr. O’Rourke outperformed Mr. Cruz by about 3,900 votes, a review of precinct-level election results found. The same set of precincts voted for Mr. Hurd over Ms. Jones by nearly 4,700 votes. Mr. Hurd won the district by just over 900 votes.
“We know exactly what the Beto bump was and it was amazing,” said Mr. Smith, the liberal activist. “But my assessment was, for Democrats, as well as we did this last election cycle, we would have had one more seat if Beto had been on board with Gina Ortiz Jones.”