FACTBOX: Scenarios in political race

(Reuters) - Republican presidential candidate John McCain was the all-but-certain nominee of his party after rival Mitt Romney dropped out last week but former Arkansas Gov. Mike Huckabee continues to pile up some wins. Democratic candidates settled in for a long battle.

Here are some scenarios for the presidential nomination battle in the coming weeks:

* Illinois Democratic Sen. Barack Obama, who emerged from the 24-state Super Tuesday battle on February 5 in a virtual draw with New York Sen. Hillary Clinton, fared well in Saturday's elections in Louisiana, Washington, Nebraska, and looks poised to do the same in Maine, Maryland, Virginia and the District of Columbia.

But since Democrats distribute delegates among candidates in proportion to their vote statewide and in individual congressional districts, those who lose a state can still come away with a big chunk of delegates.

By the end of February it is likely neither Clinton nor Obama will emerge with a significant lead in delegates. Clinton is focusing on contests in delegate-rich Texas and Ohio on March 4 as her best chance to gain a significant edge in delegates as advisers to both candidates are predicting the battle could last into the summer.

* Clinton, a former first lady, is well known to voters and has maintained a lead in national polls, even as Obama won early state contests in Iowa and South Carolina and gained momentum with celebrity endorsements and huge crowds attending his rallies. A longer campaign could benefit Obama as he gets a chance to introduce himself to more voters.

* A close contest could hinge on nearly 800 Democratic "superdelegates" who can support whichever candidate they want. Clinton and Obama are avidly courting those elected officials and party insiders, who account for one-fifth of the party's 4,049 delegates.

* In the Republican field, McCain, an Arizona senator, emerged from Super Tuesday with a commanding lead over Romney, a former Massachusetts governor, and Huckabee. McCain's position as presumptive nominee was all but sealed by Romney's withdrawal, but he still faces opposition from conservatives who remain skeptical of his stance on taxes and the environment and his losses to Huckabee in Kansas and Louisiana could fuel that discontent.

* Huckabee, an ordained Baptist minister who is strong in the South and among evangelical Christians, said Saturday he was in the race until McCain clinches the nomination. He expects to be competitive in upcoming contests in Virginia and Texas, though he lags far behind McCain in the delegate count. Huckabee denied he was considering serving as McCain's vice president.

(Reporting by Deborah Charles and Andy Sullivan, editing by Vicki Allen)

(For more about the U.S. political campaign, visit Reuters "Tales from the Trail: 2008" online at http:blogs.reuters.com/trail08/)