Suddenly everybody is Joe Lieberman's best friend. Thrown out of his party just three months ago, the Connecticut Senator and one-time Democratic vice-presidential candidate has emerged from Tuesday's mid-term elections as one of the most powerful lawmakers in Washington. Elected as an independent to a fourth term in office, Mr. Lieberman, 64, finds himself being courted by Republicans, suddenly lacking a Senate majority. He has also received conciliatory phone calls from Democrats, who had cast him as a turncoat for supporting the President on the war in Iraq.The reason is simple: Both parties need him. With the Senate race in Virginia still disputed, Democrats remain at least one seat short of winning an outright majority and taking control of Congress. Even if Democrat James Webb ultimately defeats incumbent Republican Senator George Allen, Mr. Lieberman's vote will be crucial to Democrats seeking to impose their legislative agenda on Washington in the next two years. For Republicans, who now have just 49 Senate seats, Mr. Lieberman could be an important ally on thorny security issues like counterterrorism policy and border security.