So much for the notion that Senate Republicans genuinely had a shot at putting the Democrats on the defensive anywhere in the country this cycle. Via Breaking Blue comes news of yet another survey out of South Dakota showing Democratic incumbent Tim Johnson up by a wide margin over his underwhelming GOP challenger. And earlier this week, Rasmussen Reports released new numbers out of Louisiana calling to question the Republicans' shot in Louisiana.

Senator Mary Landrieu, once viewed as the most vulnerable Democratic incumbent this election year, has opened a significant lead over Republican challenger John Kennedy in her bid for re-election.

The latest Rasmussen Reports telephone survey in the state shows the Louisiana Democrat attracts 53% of the vote while the Republican hopeful earns just 37% support. A month ago, Landrieu was leading Kennedy by only five percentage points, 49% to 44%.

When leaners are pushed, Mary Landrieu's lead over John N. Kennedy grows to 17 points, 56 percent to 39 percent -- not exactly the range of an endangered incumbent. Louisiana is still a tough state for the Democrats to prevail in, both because of the long term trends in the region away from the Democrats towards the Republicans and because of the demographic shifts in the state in the wake of Hurricane Katrina. However, the Democratic Party -- and this includes the Democratic Senatorial Campaign Committee, the Democratic Congressional Campaign Committee, the Democratic National Committee, the state party, activists on the ground -- have been working overtime in recent months to identify voters across the state, particularly those that moved from New Orleans to Baton Rouge or elsewhere, an effort which has greatly increased the party's chances in the fall. Tack on the fact that the DSCC and the Landrieu campaign have been pummeling Kennedy in paid media, and you can see why this race appears to be moving back towards the Democrats.

And with the Democrats playing less and less defense between now and November, and the Republicans going on the defensive in an increasingly large number of states (who'da thunk it that Georgia and even Oklahoma would be tightening up at this juncture), the Democrats' shot at 60 seats in the Senate is becoming ever more real.