O’Rourke is highly popular among Texas Democrats. He came closer to winning the state, in his Senate race against Ted Cruz last year, than any Democrat has come in years. It’d be easy to imagine that Texas Democrats would be excited about having a dynamic favorite-son candidate run for president.

T hey’re not.

By a wide margin — 60 percent to 27 percent — Texas Democrats want O’Rourke to quit his presidential campaign and run for Senate. That race would also be uphill. But it would not be impossible. Only 44 percent of Texas voters approve of Cornyn’s job performance, according to Quinnipiac, with 33 percent disapproving and 23 percent not giving either answer.

Why do Texas Democrats want to see a second O’Rourke Senate campaign? I can’t get inside their heads, but I think their view is rational. The Democrats have enough presidential candidates, and O’Rourke doesn’t currently look like the strongest one. He would be a strong Senate candidate, though, with high name recognition and demonstrated success in winning some voters whom Texas Democrats traditionally have not.

To accomplish every major goal that Democrats have — fighting climate change, reducing economic inequality, improving health care and so on — the party must win the Senate. Doing so in 2020 would require winning a net of three Senate seats as well as the White House (because the vice president can break a tie). One Democrat, Doug Jones in Alabama, is likely to be an underdog next year, and his defeat would mean the party has to win four seats elsewhere. The party’s best opportunities are in Arizona, Colorado, Georgia, Iowa, Kansas, Maine, Montana, North Carolina and Texas, although most of those states lean Republican.

It may be too late for O’Rourke to run for Senate. Another impressive Democrat, M.J. Hegar, has already announced that she is running against Cornyn. But I think Democratic voters in Texas are right to be putting such a high priority on the Senate. Winning the White House isn’t enough for the party to make the changes its presidential candidates are promising.