Third if you exclude Ohio's then-retiring (now retired) George Voinovich.
National Journal scored Lugar as a 63.7 on their conservative scale. They scored the most liberal Republican (Voinovich) at 60.7.
The American Conservative Union scored Lugar as a 71. They scored the most liberal Republican (also Voinovich) at 63.
Lugar was also "beat out" for most liberal Republican senator by the ladies Snowe and Collins from Maine.
Scott Brown, who took Ted Kennedy's seat representing the People's Republic of Massachusetts, is rated as more conservative than Dick Lugar.
Lisa Murkowski, who was appointed to her seat by her father and was beaten in the Republican primary only to run as a write-in candidate, is rated as more conservative than Dick Lugar.
Bob Bennett of Utah, who lost a conservative convention floor challenge for being too liberal, was likewise rated as more conservative than Dick Lugar.
Orin Hatch, who is often spoken of alongside Lugar as a target for the Tea Party and conservatives in 2012, is rated as significantly more conservative than Dick Lugar.
Heck, John McCain was way more conservative than Lugar (he topped both the NJ and ACU ratings this year).
No wonder Dick Lugar is spoken of as Obama's favorite Republican.