An absolute immigration moratorium and reparations for American blacks and American Indians who are verifiably able to prove they are at least third-generation in residency, with a sunset provision that takes effect in twenty years if and only if the official poverty rate is under 10.0%. The annual reparation amount per eligible adult is $1,000 a month, indexed to the CPI over the twenty-year period, an amount that comes to more than half the contemporary difference in median incomes between white and black/American Indian households. With around 30 million people eligible, this comes to $360 billion annually–less than 10% of the current federal budget.
Could a Republican win on this? It seems conceivable to me. It takes the leading issue of concern for the Republican electorate and pairs it with a real benefit for the rest of Old America that would generate a lot of vociferous support from American blacks, making it exceedingly difficult for the left to attack.