Obama and Edwards each have an excellent chance of winning Iowa:
In the New Hampshire race, Obama and Hillary are closer, and Edwards has more ground to make up:
But Nevada and South Carolina aren't nearly as close; Hillary is well ahead in both early states. And the national picture (which largely mirrors the Huge-Tuesday semi-national contest) gives Hillary an even bigger lead in so many different states that it will be very difficult to take her on in every one of those states:
If Obama or edwards are going to catch Hillary, they need to do so early - their chances are best in Iowa, next best in New Hampshire, and then it drops off sharply if they miss those two opportunities.
If Obama or Edwards win Iowa and Hillary finishes second, BOTH the winner AND HILLARY go into New Hampshire with a bump (traditionally, first in Iowa gets a large bump in New Hampshire, second gets a decent bump, third suffers a dip in New Hampshire).
If Obama or Edwards squeaks a narrow win over Hillary in Iowa and Hillary holds on for a narrow win in New Hampshire, they go forward into three weeks of contests where Hillary has a huge lead in almost every state.
To beat Hillary, it is Obama's and Edwards' best hope to win Iowa and to see Hillary finish third. If Obama wins Iowa and Hillary comes in third, Obama goes into New Hampshire with a big bump and she comes into New Hampshire with a dip; and under those circumstances, Obama likely wins New Hampshire. If Obama and Hillary both go into New Hampshire with post-Iowa bumps, Obama's prospects of winning New Hampshire are not as strong. The reasoning for Edwards is the same, but he has a larger margin to make up in New Hampshire (the two latest New Hampshire polls both show Edwards 10% behind Hillary).
The goal for EVERY candidate is to win Iowa. That's Hillary's goal, too, and it must be Obama's goal and Edwards' goal and Richardson's goal, etc.
Some analysts note that Hillary wants Edwards to do better in Iowa than Obama. Well, if Hillary can't win Iowa, would Hillary rather lose Iowa to Edwards than Obama? Yes (because Obama is closer to her in New Hampshire). Would Hillary rather lose to Richardson than Edwards? Yes (for the same reason). Would Hillary rather lose Iowa to Biden than Richardson? Yes (because Richardson is closer to her than Biden in New Hampshire).
Just as Hillary would rather lose to Edwards than Obama, so too should Obama hope to win, but if he can't, he better pray that he loses to Edwards instead of losing to Hillary (because then she'll likely win New Hampshire, too, and probably run the table).
Likewise, Edwards hopes to win Iowa, but if he can't win there, he would rather finish a close second behind Obama than a close second behind Hillary.
Obama and Edwards share a common hope: to win Iowa while beating Hillary as soundly as possible to stop her momentum in Nevada and South Carolina and the Huge-Tuesday states, and that means pushing her to third in Iowa by any means necessary.
Aside from the fact that each wants to win, Obama's goals in Iowa are not inconsistent with Edwards' goals there.