Leo's placement as the Vice President part of the ticket meets with some criticism from the political pundits and is called into definitive question when a poll puts the ticket only nine points behind, but shows Leo lagging. The investigation into the space shuttle leak continues at the White House.
The White House ends the internal investigation, giving Vinnick a chance to take pop shots at the Democratic Party and Santos. Josh brings in a new person to the campaign to head communications and she immediately runs contrary to Josh's idea of no negative campaigning. Greg Brock is jailed after he refuses to reveal his source. The press gets ahold of a picture of a bed that Santos and his wife demolished together.
Vinick and Santos continue to vie for voters by letting their messages come out and trying to undermine their opponent.
Bartlet's Middle East peace plan literally comes under fire as a major player dies in a suicide bombing even as the Senate looks into the information leak in the White House. A mysterious Mr. Frost appears before CJ and alerts her that there will be additional assassinations. Leo receives a subpoena. Santos handles questions on faith and religion's place in education. Toby confesses to CJ that he's the leak.
Even as Toby faces the ramifications of being the White House leak, Josh confronts some tough choices in personnel on the campaign trail.
An independent ad attacks Matt Santos's stance on abortion and both campaigns have to contemplate negative advertising. Josh works with Bruno to ensure a debate between the candidates. Will is attacked by the press when he can't comment on Toby's dismisal and outing as the White House source. Santos and Vinnick agree to a debate.
The two candidates, Vinick and Santos, take part in a live and open debate.
Santos faces a political minefield when just before a visit to a predominantly African-American Los Angeles church, a Hispanic LAPD officer guns down a surrendering black teen. CJ gives up planning a White House wedding for Ellie when trouble erupts between China, Kazakhstan and Russia. Josh visits Toby.
Bartlet must try to rectify a disintegrating situation between China and Russia over oil while his daughter gets married in the White House. Josh struggles with dwindling campaign funds and the necessary ad buys.
Josh and Lou worry about Leo's debating ability. Santos opts for a break to spend time with his family, but a tabloid picture of his wife creates tension.
Bartlet tries to broker peace between Russia and China even as Danny informs CJ of a rumor that his son in law is "banging the nanny".
Bartlet handles the crisis of a domestic nuclear reactor on the verge of exploding. In an effort to avoid an explosion, they have to release radiated steam that exceeds EPA standards for an acceptable dosage. Josh suggests that Santos not politicize it as the news will attack pro-nuclear policy Vinick.
Vinick and Santos' teams both try to deal with the ramifications the averted nuclear fallout has on their campaigns. Meanwhile, Bartlet attempts to contain a crisis in Asia.
Vinick and Santos make their way into the final two weeks of campaigning before the election. Both find themselves in different situations when they encounter a prominent athlete and try to seal up California's voters.
Santos and his campaign team roll into the Rock the Vote event. Toby faces pressure from Blake to give up his source, which puts a strain on his attempts to bond with his children, all the while trying to further Santos' Latino voter base. Meanwhile, Helen attempts to reach out the Latino community with a speech to a Latina organization, only to yield mixed results.
The night before Election Day makes for interesting bedfellows. Josh stresses over returns. Meanwhile, CJ is faced with her future job offers. Anabeth makes a startling discovery.
The election results trickle in and all sides are waiting nervously. Santos must deal with the possibility of losing his Vice Presidential hopeful, while Vinick and his team begin to clash.
Bartlet and the gang come together to pay there respects to Leo. This has an impact on Santos, as Leo was his running mate.
The President-Elect goes behind Bartlets back and talks to the President of China, offering a different position on foreign policy than he and Bartlet had originally discussed. Because the two don't see eye to eye on this particular matter, things get a little uncomfortable.
As Bartlet's administration prepares to transition in the Santos administration, CJ is faced with what to do with her future. Will is also in a position of uncertainty about what is to come.
The Bartlet Administration prepares to leave the White House and The West Wing. While Santos and his winning camp are nervously gearing up for the presidential inauguration, current President Bartlet, CJ and the others fondly look back as they prepare to leave the White House forever.