Marc Ambinder estimates:
90,000 independents choose Obama.
60,000 independents choose McCain.
260,000 votes for Democrats
240,000 votes for Republicans
So — about 25% of the Republican primary vote will be comprised of independents.
And 33% of the Democratic primary vote will be comprised of independents.
The road forward for John McCain is clear: run close to even among Republicans and get the majority of independents.
A 500,000 project splits the difference between the last presidential electon (674K) and the last gubernatorial election (417K).