Are investors more prone to vote Republican? There is evidence to indicate just that. Ramesh Ponnuru has some thoughts here.
A January 1999 Rasmussen Research poll found that in almost every demographic category, people who owned stocks were more likely than non-investors to support a capital-gains tax cut and to identify with the Republican party. Men who didn’t invest, and made between $20,000 and $40,000 a year, favored the Democratic party by 12 percentage points. Male investors with the same income favored Republicans by 3. Six percent of black non-investors supported Republicans, versus 21 percent of black investors. Republicans lost non-investing government employees by 21 points; they lost investors in the public sector by only 4.
The whole article is well worth reading — in particular the conclusion. Investors may be more likely to vote Republican, but it is just one factor in the choice of which party to vote for. Republicans will need to do more than just be pro-stock market.