SCENARIOS: How Obama, McCain are faring in key states

(Reuters) - Next week's U.S. presidential election will be decided in a handful of battleground states where opinion polls show Democrat Barack Obama mostly in the lead against Republican rival John McCain.

Obama, who leads in virtually every national opinion poll, is also ahead in all the states won by Democrat John Kerry in 2004 as well as in several states won by Republican President George W. Bush, recent polls show.

New polls released on Tuesday and Wednesday showed Obama solidifying his lead in Colorado, Ohio and Virginia, all states seen as potentially crucial in the November 4 election.

The victor will need 270 electoral votes to win the Electoral College and capture the White House.

The president is determined not by the most votes nationally but by a majority of the Electoral College, which has 538 members allotted to all 50 states and the District of Columbia in proportion to their representation in Congress.

Each state, except Maine and Nebraska, awards its votes to the candidate who gets the most votes in the state. Maine and Nebraska split them by congressional district.

Here are some battleground states with their electoral vote totals, 2004 results and recent details about the contests in each state.

* Colorado -- Nine electoral votes. Bush beat Kerry 52 percent to 47 percent in the state in 2004, but since then, Democrats have won the state Legislature and governor's office. The two most recent polls put Obama ahead by 8 and 9 points.

* Florida -- 27 electoral votes. Bush beat Kerry 52 percent to 47 percent in a state known for the disputed result that decided the 2000 election. Florida is a classic swing state with many older voters who could favor McCain along with Jewish voters who are normally Democratic but have been wary of Obama. Two polls released on Wednesday gave Obama a 2-point lead while a Tuesday survey showed him 7 points ahead.

* Indiana -- 11 electoral votes. Bush beat Kerry by 20 points in 2004 in a state that last voted for a Democrat in 1964. But it borders Obama's home state of Illinois and he has poured resources into his Indiana campaign after finishing a strong second to Sen. Hillary Clinton in the May Democratic primary. One poll on Tuesday had Obama leading by 1 point while another showed McCain with a 2-point edge.

* Missouri -- 11 electoral votes. Bush beat Kerry 53 percent to 46 percent in 2004 in a classic battleground with a mix of urban centers and conservative rural areas. The race looks tight, with one Monday poll saying the candidates were dead even in the state and another giving a 1-point edge to Obama.

* New Hampshire -- Four electoral votes. Kerry beat Bush by 1 point in 2004. McCain's history of big primary wins in New Hampshire in 2000 and this year gives him hope he can take the state in November. Democrats captured both the state's seats in Congress and gained control of the state Legislature in 2006 in an anti-Republican wave on which Obama hopes to capitalize. The three most recent polls all show Obama with a significant lead, in one case by as much as 25 points.

* New Mexico -- Five electoral votes. Bush beat Kerry by fewer than 6,000 votes in 2004. As the senator from neighboring Arizona, McCain is familiar to many New Mexico voters, but he will have to battle Obama for the growing bloc of Hispanics, who make up more than 40 percent of the state's population. Four recent polls put Obama ahead by 5 to 8 points.

* Nevada -- Five electoral votes. Bush beat Kerry by 20,000 votes in 2004 in a state won by Republicans in eight of the past 10 presidential elections. As in New Mexico, the burgeoning Hispanic population will be crucial -- it now makes up nearly a quarter of Nevada's residents. Two of the three most recent polls gave Obama leads of 10 and 12 points respectively, while the third had his lead at 4 points.

* North Carolina -- 15 electoral votes. Bush beat Kerry by 12 points in 2004, even though the Democratic vice presidential nominee, John Edwards, was from the state. More than one-fifth of the population is black and an influx of transplants to high-tech urban areas have given Obama a chance. The race looks tight with one Wednesday poll showing Obama ahead by 2 points and another this week describing the race as a tie.

* Ohio -- 20 electoral votes. Bush beat Kerry by about 120,000 votes in the state that ultimately decided the 2004 race. No Republican has won the White House without Ohio, and McCain will have a hard time piecing together a win without the state. Two of four recent polls gave Obama 9-point leads, another showed him up by 7 points and the fourth showed a 4-point lead.

* Pennsylvania -- 21 electoral votes. Kerry beat Bush 51 percent to 48 percent in 2004, but Pennsylvania is one of a handful of states won by Kerry where McCain's camp had seen a chance to reverse the result. Obama appears to have solidified an impressive lead with four of the six latest polls giving him a double-digit advantage in the race.

* Virginia -- 13 electoral votes. Bush won fairly easily by 9 points in 2004 in a state that has not gone Democratic in a presidential election since 1964. But Virginia's trend has been toward Democrats in recent state elections amid dramatic growth in the Democratic-leaning northern suburbs of Washington, D.C. The two most recent polls both had Obama ahead by 7 points.

* Wisconsin -- 10 electoral votes. Kerry won by 11,000 votes out of more than 3 million in 2004, but Obama has held a lead for months in a state where he crushed Hillary Clinton in a February Democratic primary showdown. A Tuesday poll gave Obama a 9-point lead.

(Writing by Andrew Quinn in Washington; Editing by Vicki Allen)