A quick trivia question: Who are the top unelected officials in Washington?

The Supreme Court? The president's Cabinet? The Federal Reserve?

How about the six members of the U.S. Senate who were appointed, rather than elected, to their jobs?

Meet the Senate’s Never-on-the-Ballot Caucus: Roland Burris of Illinois, Michael Bennet of Colorado, Kirsten Gillibrand of New York, Ted Kaufman of Delaware, George LeMieux of Florida and Paul Kirk Jr. of Massachusetts.

That's a record number of appointed Senators in modern history -- a byproduct of constitutional politics and dumb luck. And there could be more by the end of the year.

This group could have a profound influence on public policy, with big votes on major legislation on the near horizon, and the sheer number of them as has set off a debate about the best way to replace a departing U.S. Senator.

Unlike vacancies in the House of Representatives, which always are filled by special elections, Senate vacancies are often filled when the state's governor appoints a successor. Though occasionally controversial, the practice has been mainstream enough to last for almost a century.

The election of President Barack Obama sent the number of Senate vacancies through the roof.

The first sitting senator since John Kennedy to win the presidency, Obama snagged three of his Senate colleagues to serve in his administration. That was followed by the resignation of Florida Sen. Mel Martinez and the death of Sen. Ted Kennedy of Massachusetts.

Meantime, Sen. Kay Bailey Hutchinson (R-Texas) has said she may leave office before the end of the year to run for governor.

Naturally, the more seats become vacant, the greater the odds become for controversy in how replacements are handled.