The national branch of the Democratic Party dedicated to electing liberals to the United States Senate has canceled an ad buy for next week in Kentucky. The estimated $292,000 purchase was intended to help liberal Jack Conway in his race against conservative rival Rand Paul.

The move may be a sign of triage on the part of the Democratic Senatorial Campaign Committee (DSCC). With so much turf to defend in 2010, the organization needs to reserve funds for the most critical races. The fact that Republicans are competitive in Democratic strong-holds like West Virginia and Wisconsin doesn’t help, either.

We’ll see more of this as the election nears. Democrats considered too far gone will be largely abandoned by the national party in favor of candidates with a slight lead or small deficit. It’s not unusual in politics, but Democrats certainly didn’t want to be the party using triage in 2010.