Pundits are pointing to President Barack Obama's recent decline in public opinion polls, and saying that he may now become another "lame duck" president, unable to accomplish much during his final term in office.
That has happened to other presidents. But it is extremely unlikely to happen to this president. There are reasons why other presidents have become impotent during their last years in office. But those reasons do not apply to Barack Obama.
The Constitution of the United States does not give presidents the power to carry out major policy changes without the cooperation of other branches of government. Once the country becomes disenchanted with a president during his second term, Congress has little incentive to cooperate with him -- and, once Congress becomes uncooperative, there is little that a president can do on his own.
That is, if he respects the Constitution.