After a short interview process that was widely viewed as a formality, President Obama nominated Elena Kagan to fill Justice Stevens' Supreme Court seat. Kagan, currently the Solicitor General, nearly missed out on joining the Court the last time a seat was open. However Sonia Sotomayor was nominated and then confirmed to fill that vacancy.
Viewed as relatively moderate, it should not ultimately be difficult for Kagan to get through the confirmation process. However, that does not mean that she will be able to entirely avoid some difficult questions from Republican Members, particularly in an election year.