Calista Flockhart and Matthew Rhys, Brothers & Sisters

To make her political dreams come true, Brothers & Sisters' Kitty will need the full support of the Walker family.

But that doesn't mean she'll get it.

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In Sunday's episode (10/9c, ABC), Kitty (Calista Flockhart) polls the entire Walker clan about her plan to campaign for the soon-to-be-vacant senate seat left behind by her husband, Robert (Rob Lowe). Three guesses how that ends up.

"They all decide that they should take a vote like they used to do for family vacations," executive producer David Marshall Grant tells TVGuide.com. "But Nora [Sally Field] decides that if it's going to have meaning, it should be anonymous. So, it ends up that there's one 'No' vote, and Kitty's got to figure out who the 'No' vote is."

Distracting Kitty from her mission will be Kevin (Matthew Rhys), who asks his big sister to join him at his high school reunion for moral support. "Facing high school is a challenge for him," Grant says, adding that Kitty goes along to feel Kevin out about taking a job on her campaign staff.

See photos of the Brothers & Sisters cast

But Kevin has more on his mind. The episode will also reveal whether Kevin and Scotty's surrogate responds to in vitro fertilization. Grant won't say what happens with the possible pregnancy, but he suggests the prospect of fatherhood may change Kevin's career goals.

"Kevin's spent the whole series being a corporate lawyer, and then he moved right into being Robert's communications director," Grant says. "So he's going to be facing real decisions with his life, and I think he's definitely reaching a turning point. The impending parenthood and realizing that he doesn't necessarily want to stay in politics with Robert is going to be a big source of Kevin's story."

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With or without Kevin, Kitty's campaign may be sidetracked by none other than Robert. "He is such a big personality, and I think he will perhaps go out campaigning for Kitty," Grant says. "We might see some Bill Clinton-like situations when he is campaigning for his wife, and I think there could be some conflict there. Robert is deeply committed to his wife's winning, and so that may take him to doing things that are certainly well-intended but may also cause some problems."

Which Walker do you think will be the voice of dissent?