A head to head comparison of the Oregon 2012 General Election gives us an idea of the break down of the voters.    

Barack Obama received 937,321 (56%) votes, beating Mitt Romney who gained 733,743 (44%) by 203,578 votes in Oregon.

Mitt Romney won 26 counties whereas Barack Obama won 10 counties in the total of the 36 counties in the State of Oregon.

Presidential General Elections

During the 2012 General elections, over 122M total number of votes were cast. Barack Obama got 62,614,654 (62.6 Million) over Mitt Romney's 59,141,654 (59.1 Million). He won the popular vote by 3,472,979 (3.4 Million). His victory at the State of Oregon (with 937,321 votes) represents 1.5% of his popular vote victory. The remaining 49 states contributed to the remaining 98.5% popular votes victory.

Top 15 Counties in Primary Elections vs General Elections

All Candidates (General Elections)

These 15 counties play an important role in these Primary elections. If a candidate, can get a sizable majority in the larger counties (Multnomah, Washington, Clackamas), it becomes very difficult to win majorities in the smaller counties without voter outreach and increased voter participation in them.

Top 15 Counties Comparison in Primary Elections vs General Elections

General Elections
Barack Obama

General Elections
Mitt Romney

Multnomah, Washington, Clackamas, three of the larger counties, voted in favor of Obama, giving him a 237k vote advantage. However, Romney's steady win in the less dense counties wasn't enough to catch up, making Obama gain an upper hand in the State of Oregon.

Related References: 2016 Oregon Primary Election Story, 2016 Oregon General Election Story, 2020 Oregon Primary Election Story, 2020 Oregon General Election Story