By John Zogby
John McCain has his work cut out to win the battleground states
With the 4 November US election just three weeks away, Senator John McCain's Electoral College routes to the White House have narrowed.
Our Zogby International daily tracking polls now show Mr McCain consistently trailing Senator Barack Obama by a small margin in the popular vote.
The world knows from the 2000 election that a candidate can win the election with state-based Electoral College votes, while losing the popular vote.
President George W Bush trailed Al Gore by 0.5%, but surpassed the number of electoral votes needed by one.
In 2004, Mr Bush won the popular vote over Senator John Kerry, 50.7%-48.3%, and the electoral vote, 286-251. With 538 in total, it takes 270 to win.
We could see another such photo finish this year, but only if Mr McCain rebounds. For him to win, he could hold on to all of the states President Bush took in 2004, or wrest some of the Kerry states away from Obama. Here are the possible scenarios.
Holding the Bush States
One of the states President Bush won in 2004, Iowa (7 electoral votes), is now considered safely in the Obama column. That drops the 2004 Republican advantage to 21 electoral votes.
Mr Obama is keen to put the toss-up state of Ohio in his column
Two closely contested states were the bedrock of both Bush victories: Ohio (20 electoral votes) and Florida (27). It becomes exceedingly difficult for Mr McCain to win without holding both of these states.
Early in September, before the world banking crisis and the debates, Mr McCain held clear leads in both states. Now, the race has closed, and some polls show Mr Obama ahead.
Ohio is perhaps the nation's prototypical state, with Democratic bases in large cities and university centres, and Republican camps in small towns, exurbs and rural areas. Financial fears cross demographic borders, as does the inclination to blame the party in power and look for new direction. That makes Ohio a true toss-up.
Florida is more unique, with a mix of deep South culture, Hispanic and African-American minorities, retirees and young transplants seeking opportunity and sunshine.
The same economic forces have rocked Florida, and Republican vice-presidential candidate Governor Sarah Palin's conservative populism may be causing discomfort among the elderly voters originally from big cities in the north, especially Jewish retirees. Florida is very much in doubt.
Mr McCain could certainly win both Ohio and Florida. However, that is not enough.
To become president, Mr McCain must also defend two southern states that have been safely Republican.
These are Virginia (13 electoral votes) and North Carolina (15), which have done well economically and attracted young emigres from more depressed northern states.
Mr McCain needs to hold traditionally Republican states like Virginia
Mr Obama and Mr McCain are now deadlocked in both. Even if Mr McCain holds all the other 2004 Bush states except Iowa, losing either Virginia or North Carolina would drop him below 270 electoral votes.
Mr McCain has more ground to defend in the West. Bush won Colorado (9 electoral votes), Nevada (5) and New Mexico (5) by narrow margins. Races in all three are again very close, with New Mexico and Colorado leaning ever so slightly to Mr Obama.
Hispanics have been swing voters in these states, and right now they favour Mr Obama. Losing any one of these states would not be fatal to McCain, but two could be.
Another Bush state up for grabs is Missouri (11 electoral votes). Missouri will be close, with Mr McCain and Mr Obama trading the lead in the polls over recent weeks.
Turning Blue States to Red
Given the Republican wins in 2004 and 2000, the loss of any states that voted Democratic would be very damaging to Obama. One of those states that the GOP always targets, Michigan (17 electoral votes), has already been effectively taken off the board by Mr McCain, who pulled out his advertising and staff.
That surprised many (including his running mate Sarah Palin). This may have been a wise use of resources by McCain, who, unlike Obama, is constrained in raising money due to his agreement to take public financing.
Mr McCain surprised many, including Sarah Palin, by pulling out of Michigan
However, the Michigan decision sends a negative message about Mr McCain's chances of picking up two other Midwestern industrial and farming battleground states, Wisconsin and Minnesota, both with 10 electoral votes. Mr Obama leads in both, but has not pulled away.
The main target for Mr McCain remains the northern state of Pennsylvania (21 electoral votes), where Senator Hillary Clinton easily defeated Mr Obama in the Democratic primary. Pennsylvania's big cities of Philadelphia and Pittsburgh are balanced by rural areas that can have more in common with the South.
The state's Democratic Governor Ed Rendell in February asked whether some "conservative white voters are ready to vote for an African-American".
That remains a question, but it could be trumped by economic worries in what is a classic rust-belt state. Mr Obama's rise in Pennsylvania polls has coincided with fears about the credit crunch and falling stock prices. Right now, Mr Obama should be favoured to win Pennsylvania.
Another target is New Hampshire (4 electoral votes), won by President Bush in 2000 but by Mr Kerry in 2004. If Mr Obama succeeds in holding it in 2008, this could help to tip the balance in his favour.
Can McCain Win?
With so few opportunities to take states from his Democratic rival, Mr McCain's most likely path for victory is to limit his losses of 2004 GOP states to Iowa. Margins remain tight, putting Mr McCain in position to win any of these critical states. Winning nearly all of them is his challenge.
Mr McCain must seek to limit his losses of 2004 Bush states to Iowa
Finally, and perhaps most importantly, this is indeed an historic and different US election. Mr Obama is the first ever African-American major party nominee.
I join most polling professionals in doubting that significant numbers of white voters are being untruthful when they say they will vote for Mr Obama (the so-called Bradley or Wilder effect).
However, measuring racial factors and how they will impact turnout and voting is one of the more difficult tasks for pollsters. How well we have done won't be known until election day.
On the flip side, Mr Obama has obviously energised both minority and young voters, two groups that historically turn out in lower numbers.
Democrats have scored very well in registering both. If they vote in numbers that Democrats hope for, Mr McCain's chances of running the table of contested states will be very, very slim.