The Founders never planned for the direct election of senators, so there is no mechanism for recall. Senators were to be appointed by state legislators to represent the interest of that state in D.C. The seventeenth amendment was a huge mistake because six years is too long for voters to wait to fire lousy senators.
Its funny, the 17th amendment was supposed to prevent exactly what we see in the Obama administration with Obama acting as the party boss and handing out political favors accordingly. I read somewhere that Obama has appointed more senators to high ranking positions than any other president.