Why Pick One Issue

In this post, Matt Yglesias points out that you don't always get to pick the issues that dominate an election. The Republicans will have some success making the 2006 elections about national security even if the Democrats want it to be about corruption. But why the hell do the Democrats have to pick only one of these? The main issue, as I see it, is that those who are systematically corrupt and always place their own personal gain above the welfare of the nation cannot be trusted with national security. We are seeing the consequence of having entrusted our security to this Republican leadership so lacking in integrity and ethics and the results are not pretty. The long, brutal attrition that is the Iraq war is a direct consequence of the corruption which pervades the Republican party. Going back, we should not have been surprised that the September 11 attack was able to do as much damage as it did, and kill as many Americans as it did, given the corruption which pervades this White House. Why cannot Democrats argue that the revelations of Abramoff and Savavian and the rest demonstrate a culture of corruption and that that culture of corruption is the most serious threat to national security that we face.

Indeed, given the Martin Luther King address given by Al Gore, see here, it is clear that Democrats can argue this point. Why then are so many on the left arguing that we can only make one point at a time?