Yes, this is yet another Nixon related what if?
After running for Governor of California and losing in 1962, Nixon moved to New York and took a job in a law firm.
What would have happened if Nixon had skipped running for Governor of California and moved to New York in 1961? And then he ran for Mayor in 1965?
Presumably anyone the Republicans nominated for Governor of California in 1962 would have lost to the elder Brown, though I could be wrong on this.
The Republican candidate for Mayor of New York in 1965 did win IOTL. The only President so far to run for that office, Theodore Roosevelt, as a Republican, came in third.