The daily phone calls. The midnight e-mail. And, when college lets out, those dinner table declamations? Oh, please.

Senator Barack Obama’s devotees just won’t give their parents a break.

As the race for the Democratic presidential nomination continues, youthful volunteers for each candidate have been campaigning with bright-eyed brio, not only door-to-door but also at home. But the young supporters of Mr. Obama, who has captured a majority of under-30 primary voters, seem to be leading in the pestering sweepstakes. They send their parents the latest Obama YouTube videos, blog exhortations and “Tell Your Mama/Vote for Obama!” bumper stickers.

Megan Simpson, a Penn State senior, had not been able to budge her father, a Republican. But the day before the deadline for registering for the coming Democratic primary in Pennsylvania, she handed him the forms and threw in a deal-sweetener as well. “I said, ‘Dad, if you change your party affiliation in time to vote for Obama,’ ” recalled Ms. Simpson, 22, an Obama campus volunteer, “ ‘I will get you the paperwork the day after the primary if you want to switch back to being a Republican.’ ”

Thus did Ralph E. Simpson Jr., 50, construction company owner, become a newly minted Democrat. “I probably will switch my affiliation back,” Mr. Simpson said, “but I haven’t decided who I will vote for in the general election. If Meg keeps working on me, who knows?”