So why don't I think 60,000 votes out of the 377,000 cast for Santorum came from democrats? Actual election returns. If you look at Michigan maps, especially 2004, you'll see how many counties votes for democrats and how many voted for republicans, along with which ones. A lot of the democrats in Michigan are concentrated in a few areas. This can be seen with the congressional districts. Most of the democrat districts, especially under the new allocation, are 60% or more democrat. All of those districts except the 13th district, votes for Romney, not Santorum. Most of the Republican held districts voted for Santorum.

GOP held Districts:
CD 1, 2, 3, 4, 6, 7 - Santorum
CD 8, 11 - Romney

Dem districts:
CD 5, 9, 12, 14 - Romney
CD 13 - Santorum

That alone doesn't tell the whole story. There are pockets of democrats in the republican districts and pockets of republicans in the democrat districts, but it is not hard to find samples in democrat areas. One thing is clear, most of Santorum's votes were from Republicans. Most of Romney's votes were also from Republicans. Democrats don't win Livingston County in primaries. Democrats don't win Ottawa County in primaries.

I'll start with Pontiac and Auburn Hills. Why? Pontiac is a democrat stronghold in Oakland County. It's 80% democrat every election. It also was ground zero for an open state rep election and charter issue as well, so there is a reason for the democrats to vote there besides mischief. Here's the results for that state rep district, strictly in Pontiac itself, followed by Auburn Hills, a democrat leaning area, but not nearly on the same scale. Republicans often get 45% of the vote there, although McCain bombed and Obama broke 60% there.

Pontiac:
Tim Greimel (D) - 88.10% - 5,746
Bob Gray (R) - 11.90% - 776

Auburn Hills:
Bob Gray (R) - 50.53% - 1,338
Tim Greimel (D) - 49.47% - 1,310

Gray overperformed in Auburn Hills, probably due to the presidential primary. Here's the primary results in both areas there.

Auburn Hills: (population about 21,500)
Romney - 743 - 40.23%
Santorum - 639 - 34.88%
Paul - 279 - 15.23%
Newt - 117 - 6.39%
Obama - 782 - 93.65%
Dem Uncommitted - 53 - 6.35%

Pontiac: (Population about 59,000)
Santorum - 575 - 41.01%
Romney - 364 - 25.96%
Paul - 317 - 22.61%
Newt - 92 - 6.56%
Obama - 4881 - 97.72%
Dem Uncommitted - 114 - 2.28%
Most dems stayed home in their primary, even with just Obama there with "uncommitted". About 15-20% of Pontiac often votes Republican and about 45% of Auburn Hills often votes Republican. The Republicans in Pontiac are more likely working class social conservatives and small business owners. Those in Auburn Hills tend to vary. Auto executives are there, and it is also Tom McMillan's old stomping grounds before he went to the Rochester area. Both Romney and Santorum received more votes in Auburn Hills than Pontiac. Ron Paul was another story.

Here's one of the most Republican areas of Oakland County. Brandon Township. I'm going to follow that with nearby Oakland Township. They are both republican strongholds in Oakland County. There were not a lot of crossovers here. Both of these areas are consistently over 60% Republican areas.

Brandon Twp:
Santorum - 802
Romney - 775
Paul - 275
Obama - 135
D Uncommitted - 22

Oakland Twp
Romney -  1736
Santorum - 870
Paul - 271
Obama - 188
D Uncommitted - 17

Both of those are North Oakland Republican strongholds. The areas there are both republican areas voting for different republican candidates. One's a little more rural than the other, but neither are Bloomfield Hills where there is more of a homer factor.

Macomb County results varies some as well. The strongholds there are less like Pontiac and are whiter, with some republican pockets, and a lot of union independents. There wasn't a real pattern one way or the other.

Warren (about 60% dem):
Romney 4229, Santorum 4074, Paul 1337, Obama 3066, D uncommitted 638
Roseville's percentages were about the same as Warrens

Washington Twp (GOP Stronhold)
Romney 1932, Santorum 1347, Paul 355, Obama 376. D uncommitted 66

Utica (50/50)
Santorum 217, Romney 213, Paul 77, Obama 89, D uncommitted 28

Ray Twp (GOP Stronghold)
Santorum 261, Romney 250, Paul 74. Obama 53, D uncommitted 11

Overall Santorum won these areas:
GOP - Armada, Memphis, Ray, Richmond City and Twp
Dem - Center Line, Eastpointe,
Swing - Lenox, Utica

Santorum didn't win Roseville, Warren, or Mt Clemens which are democrat, nor Republican areas like Washington Twp, Shelby Twp, or Macomb Twp.

Obama had the most votes in Center Line, Eastpointe, Roseville, all narrowly.
Romney actually beat him in Mt Clemens. Both Santorum and Romney beat him in Warren. I think both candidates had their share of crossovers in these parts of Macomb County. Social liberals more to Romney and Social conservatives more to Santorum. I certainly didn't see a big push though one way or another, despite dem consultant Joe DiSano's advocacy of mischief.

Looking at another democrat stronghold. Washtenaw County.

Ann Arbor had less than 10% turnout outside of the 2nd Ward which is more republican than most of the city. That is a high money area, and went for Romney. The rest of Ann Arbor was mixed across the board, but hardly enough to manner. Some went to Santorum, some Romney, some Paul. Some of those were probably crossovers, but at less than 10% turnout, they could just as easily been those few republicans in the city.

Ypsi went narrowly for Santorum, but Obama had more votes there. The "rural" Ann Arbor Township precinct went for Santorum. That's also the Dominos Farms location. Whitmore Lake area went for Santorum. Augusta Twp (south of Ypsi) did as well. Probably not crossovers. Saline went for Romney. Probably not crossovers there either. These areas are matching about what I'd suspect.

I've look at different election areas across the state. I'm noting really out of the ordinary with vote patterns. 100,000 votes or even 65,000 in crossovers is very significant. If someone can point out where they would come from, I'd appreciate it. I don't see it. Not with Bay County and Saginaw County going for Romney, and if I was going to expect crossovers, it would be there.