Katrina: Bush's #1 vulnerable spot

Political Wire relays this interesting information:

"Among the many controversies surrounding the Bush Administration, its response to Hurricane Katrina is most troubling to voters," according to a new WNBC/Marist poll.

The survey found that 66% of registered voters nationwide "are bothered a great deal or a good amount by the administration's response to Hurricane Katrina. Although Democrats are most critical, 64% of independents and 42% of Republicans are bothered by how the administration handled the disaster."

The second most troubling is the Bush administration's wiretapping of Americans without a warrant, with 50% bothered a great deal or good amount.

Question: If Katrina is Bush's #1 vulnerability, why aren't Democrats making Katrina their #1 issue?