Many conservatives have been high on Alaska Gov. Sarah Palin as a John McCain running mate for some time. She’s young, truly conservative both fiscally and socially, and from what I’ve heard a good speaker and communicator of ideas. She killed the bridge to nowhere project, and wasn’t afraid to veto spending bills (i.e., stomach that Bush lacked), she as head of Alaska’s National Guard and has a son about to deploy to Iraq.

The least risky pick, from an overall electorate view, would have been Mitt Romney. He finished a close second to McCain and arguably would have won had Rudy Giuliani dropped out of the race sooner.

Like McCain, Romney isn’t especially socially conservative, and arguably less so than McCain, but he was a wiz on economics (McCain’s weak point), and even more important, could communicate those ideas (why supply-side conservative fiscalism simply works better than liberal economics).

The biggest advantage is that Romney was a known commodity, and certainly so through the course of this ridiculously long primary cycle, which started in Summer 2007. (Then again, sometimes there’s strengh in being an unknown).

Having said that, Palin does something that Romney couldn’t — truly energize the Republican base.

Here’s William Ruger in the Anchorage Daily News a few weeks ago:

Fourth, and critically, given the price of oil, Palin can help McCain focus on energy security, an issue that could be Obama’s Achilles’ heel — if the Republicans could overcome McCain’s opposition to things like drilling in the Arctic National Wildlife Refuge. The environment might be wildly popular on the coasts, but in the middle where this race will be won, a candidate who could credibly sell a plan for lower prices at the pump will move votes.

But most important, Palin could do something few Republicans seem interested in or able to do these days: Help fuse the two pillars of the Reagan Revolution, traditional conservatives and libertarian Republicans.

Palin can win the hearts of conservatives, given her strong pro-life views — views that were backed up with action this year when she gave birth to a son with Down’s syndrome. It would probably also help with these folks that her oldest son recently enlisted in the Army. And she can excite libertarian Republicans, given her fiscal conservatism as governor as well as her reputation for anti-corruption, love of guns and the outdoor life, and moderation on social issues other than abortion.

In short, Palin will provide McCain the surge he needs to win his last battle.

It’s a difficult balance for McCain. He must energize his base while not alienating the moderates and independents whom both parties traditionally attempt to woo. Go too far into the middle and your base may not show up on election day. Go too far to the right and the moderates may ebb towards Obama.

All in all, I think McCain would have been fine with either pick. Romney was the safe pick, but sometimes safe backfires. Picking Palin isn’t really rolling the dice, just a moderate risk, but the potential payoff is huge.