"down" used as a verb?

The excerpt that follows comes from the article The Honest Man by Peter Lyon from the American Heritage magazine.

He (Peter Cooper) received only one per cent of the vote. Yet time has treated his ideas most kindly. For in retrospect the impression will not down that, so far from being ludicrous, those ideas were sane, intelligent, liberal, and practical.

I'm flummoxed by the use of "down" here. Could it mean something like "deny"? (I cannot find an apt meaning in the dictionary...)

Solution 1:

According to the OED it is a US sense, which I (a British person) had never before encountered.

It is sense 2b, of verb2 of "down", meaning "to die down". Only one example is given.

2b. To die down. U.S.

1924 W. M. Raine Troubled Waters xvii. 180 The rumour would not down that one of the prisoners had turned State's evidence.

verb1 - down has to do with the application of "down", meaning feathers.

verb2 - down relates to various verbal senses to do with a downward direction.