THE HILL: Jon Tester: Senate Democrats’ Canary In The Coal Mine.

Since August, President Obama has made “running against Congress” a centerpiece of his reelection strategy, as President Truman did in 1948. But the comparison between 1948 and 2012 contains one inconvenient fact: the Senate is still controlled by the President’s own party, and that happens to be the part that is giving him the greatest trouble.

Numerous Senate Democrats – including top brass like Harry Reid, Chuck Schumer and Max Baucus – have made clear they are not going to “pass this bill” without major changes. Sen. Begich, Ben Nelson, Casey, Landrieu, Webb, McCaskill and others are openly uncomfortable with defending another fat stimulus package – this time funded with the kicker of broad tax increases.

Now skepticism is hardening into outright opposition. This week, Jon Tester, one of the three most vulnerable Democrats in the Senate, publicly opposed the Obama stimulus tax bill. What does that mean for the other two most vulnerable Senate Democrats: Ben Nelson of Nebraska and Claire McCaskill of Missouri?

What, indeed?