Senate Majority Leader Harry Reid (D-Nev.) has decided that Sen. Joe Lieberman (ID-Conn.) — one of Republican presidential hopeful Sen. John McCain’s (R-Ariz.) top supporters — can no longer attend Democrats’ weekly caucus lunches or the biweekly chairmen’s lunches used to formulate policy, senior Democratic aides said Tuesday.

The decision comes in the wake of Lieberman’s attacks on Democratic presidential nominee Sen. Barack Obama (D-Ill.) at the GOP convention last week, and essentially formalizes a deal Reid and Lieberman had cut earlier this year under which Lieberman would not attend meetings that included discussions of sensitive campaign or political issues.

Lieberman for weeks has voluntarily forgone the weekly caucus lunches and weekly policy lunches on Thursdays.