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

Mitt Romney received 420,750 (66%) votes, beating Barack Obama who gained 212,560 (34%) by 208,190 votes in Idaho.

Mitt Romney won 42 counties whereas Barack Obama won 2 counties in the total of the 44 counties in the State of Idaho.

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). Even though he lost to Mitt Romney in the State of Idaho, his 212,560 gained votes represents 0.3% of his popular vote victory. The remaining 49 states contributed to the remaining 99.7% 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 (Ada, Canyon, Kootenai), 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

Ada, Canyon and Kootenai, three of the larger counties, voted in favor of Mitt Romney giving him a 65k vote advantage. This combined with Romney's steady win in the less dense counties was enough to maintain that difference, making him gain an upper hand in the State of Idaho.

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