In an interview this week, U.S. Sen. Jeff Merkley (D-Oregon) offered a new reason he might not run for president: fear that if he doesn't seek reelection to the Senate, that could provide an opening for Republicans.

It sounds a little odd in a state that has elected precisely one Republican to statewide office since 2002.

Merkley told the NW Labor Press that he's still weighing his options.

"Because others may run," he explained. "The Republicans may get an opportunity to have a strong candidate. And I cannot let an Oregon Senate seat go to someone who is fighting for the privileged and powerful."

Oregon does not allow a name to appear on the ballot for two different offices. New Jersey, by contrast, has changed the law so that its senator, Cory Booker, can run for reelection as a senator at the same time he seeks the Democratic presidential nomination.

Merkley has received a tepid reception in Salem to the idea of changing Oregon's law to allow him to run for both seats. In a Dec. 8 Tweet, Merkley claimed he was "completely fine with that"—meaning Salem not changing the law.

But that Tweet and other remarks he's made have suggested he's going to run.

His comments to the NW Labor Press, published last week, offer a new reason for why he can't sit back and go for both seats, even as Oregon allows him to wait until March of 2020 to decide which ballot line to run on.

I am not in the luxury of being outside my Senate cycle,” he said. “So I have my Senate campaign cycle to weigh against a presidential run. Where can I be most effective in influencing these issues? It comes down to that. I’m the only senator thinking about the race who couldn’t be on the ballot for both.”

Merkley's caution gives the Republican Party in Oregon more credit than most political observers currently do.

The party took a drubbing in November's election in which the Democrats added to their majorities in both houses of the legislature. And former Rep. Knute Buehler (R-Bend), who challenged Democratic Gov. Kate Brown's reelection bid, was widely viewed as the strongest Republican candidate in years and yet he lost by a more than 6 percentage point margin.

Merkley has previously said he'll decide by the end of next month whether he's launching a run.