1: Calls for Biden to drop out rise

2: New poll shows Michelle Obama leading Trump

3: Michelle Obama's potential run gains momentum

4: Public favors former First Lady over current President

5: Biden's support wanes as Obama's prospects soar

6: Michelle Obama emerges as strong Democratic contender

7: Trump trails behind in latest poll numbers

8: Biden faces pressure to step aside for Obama

9: Will Michelle Obama enter the 2020 race?