Partisans are the types of members of Congress that vote based on the views of the political party. They are often the hardest to get to compromise. They vote along party lines about 90% of the time. They can be very reliable for figuring out if a vote will pass. It can also be very shocking when they flip and vote opposite of what the party wants. A recent example would be John McCain's recent vote in the Senate. His vote was one that had been expected, so when he voted against the measure, it was a complete shock.