2012:President McCain vs Senator Obama (read the description)

[BigVic]

Palin wins the primary but loses the general

[BigVic]

2008

President John Kerry (D-MA) / Senator Barack Obama (D-IL)
Senator John McCain (R-AZ) / Governor Tim Pawlenty (R-MN) ✓

President Kerry is better able to share the blame for Iraq and the recession than Bush IOTL. Then there's Edwards likely retiring- either in a scandal, because he demonstrated that behavior IOTL and would do something like it here, or less controversially because he would want to spend time with his dying wife. Obama really steps into the spotlight as Kerry's running mate here. Still a Republican victory but not the mandate Obama had against the Republicans IOTL. Not to mention McCain is a terrible candidate to run any time after Iraq has gotten unpopular regardless of the incumbent.

2012

President John McCain (R-AZ) / Vice President Tim Pawlenty (R-MN)
Senator Barack Obama (D-IL) / Fmr. Governor Tim Kaine (D-VA) ✓
Businessman Donald Trump (TP-NY) / Governor Sarah Palin (TP-AK)

McCain starts a war with Iran in 2009 to disarm an alleged nuclear weapons program and in support of the Green Movement protests, and a combination of the oil shock and congressional Republicans' doubling down on Reaganomics plunges the country indisputably into a second Great Depression. By the 2010 midterms, factionalism is tearing the GOP apart. None other than Donald Trump emerges to primary McCain and then run third-party.

The centenary of the 1912 election marked with the GOP incumbent losing in a landslide with the third party candidate scoring more votes and placing 2nd

[BigVic]

I think Obama would probably win, though it wouldn't be an easy victory.

Also, this timeline could potentially put us into 2 decades+ of one term presidents.

2000: Bush
2004: Kerry
2008: McCain
2012: Obama
2016: Trump
2020: some democrat?
2024: some republican?

An interesting scenario. One-term wonders in the 21st century