The Republican State Central Committee is meeting this weekend with one very big decision to make that could impact the next big race in Virginia.

Members will decide if they’ll pick their Senate nominee for the 2012 elections by primary or convention… setting up some interesting dynamics.

If it’s a convention, expect the more conservative candidate in the race to win. That’s the history of these events for years. It happened in 2001 when the Republican attorney general and lt. governor went head to head. The more conservative Mark Earley won.

It happened again in 2009 when conservative Ken Cuccinelli easily beat out two other candidates for the Republican nomination for attorney general. In fact, I’ve been told by several Republican insiders that Cuccinelli would have given Bob McDonnell a run for his money for the gubernatorial nomination in that convention, even though McDonnell is a conservative himself.

That’s the way conventions go. The most conservative candidate generally prevails.

That principle can even scare of candidates. It happened in 2008. Before the committee decided to have a convention to pick the nominee, the frontrunner appeared to be moderate Northern Virginia congressman Tom Davis. Davis figured he had a pretty good chance at winning in a primary where more moderate voters would likely have a larger voice in picking the nominee.

But with a convention looming, Davis quickly backed out, realizing he had no chance of prevailing. Instead, conservative Manassas Delegate Bob Marshall and former Virginia Attorney General, Governor, RNC Chair and GOP presidential candidate Jim Gilmore went head to head. It was a battle Gilmore should have won easily. Yet, he BARELY crawled out of the convention with his political life.

Gilmore’s razor thin victory showed his vulnerabilities. He went on to take a brutal beating in the general election against the man who replaced him in the governor’s mansion, Democrat Mark Warner. Gilmore lost every single congressional district in the commonwealth, including the most conservative, Republican districts.

Would Tom Davis have fared as poorly? It’s all speculation, but Davis’ more moderate profile would have likely appealed to more of the commonwealth’s independent, moderate voters and his NOVA roots would have made him more competitive in that voter-rich segment of the commonwealth. Would he have won? Probably not in a Democratic year that saw the commonwealth go for a Democratic presidential candidate. But, Davis likely would have made the race more interesting and competitive.

Conventions and primaries are both unpredictable, as the voter pool is small. But a convention is even more unpredictable because the pool is tiny. Roughly 10,000 people generally pick the nominee. You can do the math and tell quickly that you only need 5,001 people in a two person race and you’ve won. That’s a very, very small number.

On the flip side, primaries generally favor the candidate with the highest name ID and the most money. That can limit the impact of a popular, grassroots candidate who doesn’t have the finances to get his message out or mobilize his or her troops.

So, what will Republicans do this time around? Will they go with a convention, where the outcome it far less predictable? Or will they go with a primary, where the biggest name may prevail?

That decision… convention or primary… will have a big impact on the race and its potential candidates.