Ted and Marco would pretty much have to suspend their campaigns to block the nomination. After all...Obama could nominate a moderate, which is just as bad as a liberal in tea partiers eyes. And you know...republicans aren't the only ones who can filibuster, so a democrat might...just for fun...you know to keep Ted and Marco off the campaign trail and focused on the jobs they are being paid to do. Of course, he COULD nominate a Jew, which would open the door for anyone running against Ted to grab that Maddow tape and point to many of his supporters.
And finally, when a group that has a lower approval rating that maggot infested fish vows to block a person when they don't even know who it is - they will reinforce "the party of no". Which could come back to hurt the makeup of Congress...