New state-by-state data released by Gallup on Tuesday (chart below) shows that a majority of respondents approved of the president's performance in only 10 states plus the District of Columbia, down from 13 a year earlier.
Meanwhile the number of states where his approval rating was below 40% doubled in 2011, from 10 to 20. That list now includes New Hampshire, where his approval rating was 38.7% -- the lowest score in any of the states he carried in 2008.
Put into electoral terms, states with majority approval of Obama in 2011 account for 159 electoral votes, Gallup's Jeffrey Jones points out. Those states where he is below 40% account for 153 electoral votes.
The remaining 226 electoral votes include the key prizes of Ohio (42.1% approval), Pennsylvania (45% approval) and Florida (43.6% approval).
"His approval rating is a key indicator of his electoral vote chances, but it alone will not dictate his success," Jones writes. Voter turnout and the identity of Obama's Republican opponent will also play a role.
Nationally, Obama's approval rating in 2011 averaged 44%, down from 47% a year earlier.
Excluding the nation's capital, Obama again fared best in his home state of Hawaii, where 56.1% approved and just 38.2% disapproved of his performance. But Hawaii is also the state where his approval rating declined the most in a year, dropping 9.8 percentage points.
The 13 other states where Obama's approval rating dropped by five or more points include New Mexico, Nevada and Ohio -- each traditional bellwethers.
Obama's approval rating was lowest in Utah -- 28.6%. Wyoming, which had that distinction in 2010, was actually one of only three states where Obama's approval rating increased in the last year -- along with Connecticut and Maine.
The "red state" where Obama had his strongest numbers was Georgia, at 44.6%.