I thought Carter wins. How does Kemp get to be Vice President?
I did a couple of different models; this obituary is premised on the following:
The 1980 Election was a draw (the map I labelled my favourite) - the net effect on the popular vote numbers would be to reduce Carter's closer to OTL; increase Reagan's slightly and boost Anderson's (sees a flight of dissaffected independents from Reagan to Anderson and/or a reduction in Reagan votes increasing Anderson's relative share of the popular percentage).
In the draw Carter is re-elected in a contingent election in the House after six ballots.
Bush is elected Vice President in a contingent election by the Republican majority in the Senate.
You have a Carter-Bush Administration from Jan 20, 1981 - March 30, 1981.
Bush succeeds the slain Carter and names Jack Kemp as his Vice President under the 25th Amendment process.
Bush chooses Kemp in order to placate the economic conservatives in the Republican Party who are part of the Reaganite block that is screaming bloody murder over the outcome of the election. While they regarded President Carter as a loser who stole the election (with some justification, though he won on the Constitutional technicalities) they consider Bush in the Presidency as a usurper of the role that belongs to Reagan.
Kemp as a supply-sider gives Bush a political bridge to some of these people, and by allowing Kemp to advise on the economic policy agenda, he can implement a part of the Reagan Revolution which will shore-up his support (however grudging among economic conservatives).
With Bush's popularity low Kemp provides him with political cover, since Kemp - unconnected to what has gone before - can negotiate with Congress on policy issues to achieve legislative results. (and having been in the House for a decade or so he's got the connections and relationships to do it).
There is a variation to this too that goes something like this: Bush is largely seen as a usurper by the Reaganites, and his popularity is very low due to all of the uncertainties of his role in "Caseygate" and the conspiracy theories about his family connection to Hinckley.
The economy recovers in 1983 and early 1984, due to conservative economic policies and the reduction in the price of oil, this reflects favourably on the incumbent administration and Bush enjoys an end-of-term honeymoon in popularity associated with the economy.
This allows him to seek re-nomination and the Bush-Kemp ticket then defeats Hart-Layne-Collins, again in a narrow election. Hart attempts to raise suspicions of Republican dirty tricks during the campaign, but there is a mood of the electorate in the recovery and the go-go Eighties to forget the past and move ahead. "If its working, don't fix it."
Kemp then succeeds Bush in 1988.
A posthumous Carter receives some historical re-habilitation, but his image is not as deified as that of Kennedy and Lincoln (He joins McKinley and Garfield in the less acclaimed category of slain Presidents).
This line also perpetuates the curse of Tippecanoe for another twenty years.