In a twist on some of the primaries so far this year, national Republicans are divided over a bid by 91 year old Rep. Ralph Hall (R-TX) to win one more term in the Congress, as he faces a former federal prosecutor in a GOP runoff Tuesday in the Lone Star State.

The oldest U.S. House member in history, Hall has been in Congress since being elected as a Democrat in 1980; he switched to the Republican Party when he ran for re-election in 2004.

One of Hall's recent television ads makes no effort to avoid his age - he says his wrinkles are basically political battle scars from his time in office.

Hall is facing John Ratcliffe, who was a U.S. Attorney under President George W. Bush. In his latest ad, he tries to nicely raise the issue of Hall's age in urging a change in Congress for this heavily Republican district in Texas.

The race has split Republicans, with many big names in the GOP rallying to Hall's defense, like Newt Gingrich; Hall also won the backing of the National Rifle Association.

While Ratcliffe cannot be described as a Tea Party candidate, he has secured the endorsements of major outside conservative groups, like the Club For Growth and the Tea Party Express.

So far this year, not one member of Congress has been booted out by the voters - on May 27, the 91 year old Ralph Hall has the election stage to himself to see if that streak continues.

Upcoming Primary schedule

May 27 - Texas runoff
June 3 - Alabama, California, Iowa, Mississippi, Montana, New Jersey, New Mexico, South Dakota
June 10 - Maine, North Dakota, Nevada, South Carolina, Virginia
June 24 - Colorado, Maryland, Oklahoma, Utah