One of the big advantages Rand Paul has in the Republicans primary could be Hillary Clinton.
Paul isn’t an across-the-board dogmatic Republican. There are at least a few issues like government spying, drug policy reform, military action where Paul clearly stands apart from the rest of the potential 2016 Republican field. From a liberal perspective he is arguably even better than Barack Obama or Clinton on a limited number of topics. This makes Paul potentially appealing in the primary to Independents whose positions don’t neatly fall along the traditional partisan spectrum.
This is important since there are a number of open/mixed primary states, like New Hampshire and Virginia, where Independents or even Democrats can vote in the GOP primary.
If there is both a competitive Democratic and Republican Presidential primary this pool of potential Independent voters will be split, but if Clinton runs there might not be a competitive Democratic primary. This is how she could indirectly benefit Paul. There is a good chance she could either clear the field or effectively win the nomination extremely quickly. If she doesn’t run though we can expect a very heated Democratic contest.
Without a competitive Democratic primary Paul’s more idiosyncratic positions become more politically useful in open primary states where he could try to reach out to Independents. I can even imagine a small number of Democrats with their own primary voting for Paul in the GOP contest to send a message about opposing the NSA or military action, while still planning to vote Democratic in the general. In 2012 two of Ron Paul’s best primary performances were in the open primary states of New Hampshire and Vermont.
The impact is not likely to be huge but a few thousand vote can make the difference between a narrow win and a lose.