A key figure in the battle to revamp U.S. healthcare may soon be the U.S. Senate's little-known, mustachioed and highly respected umpire, Alan Frumin.

If Democrats, as anticipated, resort to a seldom-used procedure to ram such a bill through the Senate, it will be up to Frumin to make the tough calls on whether a long list of provisions are in or out of bounds.

You end up making all sorts of enemies, said Bob Dove, Frumin's predecessor in the $170,000-a-year post formally known as Senate parliamentarian.

Dove speaks from some experiences. In 2001, then-Senate Majority Leader Trent Lott fired Dove after Republican frustration with some of his calls on tax and budget matters.

Just months earlier, Dove had riled Democrats by declaring that a proposed tax cut could be considered under a tactic that prevented them from raising a procedural roadblock.

Here are some facts about Frumin, his job and his task:

* A graduate of Colgate University in New York with a double major in economics and political science and Georgetown Law School, Frumin succeeded Dove as parliamentarian in 2001. Frumin has the same style as Dove, said Senate Historian Don Ritchie. He's scrupulously neutral. He is also keeps a low profile and declines interviews with the news media.

* Senate Democrats are headed toward trying to pass President Barack Obama's healthcare overhaul using a procedure called reconciliation. The tactic allows passage by 51 votes in the 100-member Senate. It also forbids procedural roadblocks, which take 60 votes to clear.

*Under The Byrd Rule, named for Senator Robert Byrd, reconciliation is limited to budget issues. The rule states: A provision shall be considered extraneous if it produces changes in outlays or revenues which are merely incidental to the non-budgetary components of the provision. Frumin will handle Republican challenges regarding such questions as what's merely incidental, extraneous or even a provision?

* In private and high-stakes meetings known as Byrd baths, Frumin will take a look at these and other questions. Segments of a bill that are eliminated are called Byrd droppings.
* Frumin would make the calls, but not make the rulings. The Senate's presiding officer -- Vice President Joe Biden, Senate President Pro Tempore Robert Byrd or another designated Democratic senator -- would rule after getting Frumin's advice. The last time a ruling by the presiding officer was overturned on a Senate vote was October 3, 1996. There have been other attempts, but they were defeated.

* The parliamentarian is appointed by the secretary of the Senate, whom the chamber elects at the recommendation of the majority leader. The parliamentarian, as evidenced by the firing of Dove, serves at the pleasure of the majority leader. Dove said of Frumin: He's a straight shooter, an excellent parliamentarian, and I don't envy him.

(Reporting by Thomas Ferraro in Washington; Editing by Cynthia Osterman)