Hoynes and Russell are campaigning in New York, confident of their prospects in the California primary. Santos needs to do unexpectedly well in California in order to stay financially afloat; another third place finish will see his donors shift their money elsewhere, finishing his campaign. Santos's message of education and health care is overshadowed when California passes a law prohibiting drivers licenses for illegal immigrants. Despite the bill being widely supported by most voters, Matt cannot publicly endorse it as he's counting on the support of Latino voters, who expect him to denounce it.

WHO WILL BE THE DEMOCRATIC PRESIDENTIAL CANDIDATE? - It's the Democratic National Convention and the race to become the Democratic Presidential candidate has narrowed to three candidates: Russell, Baker and Santos. Also, Bartlet must wrestle with the decision to launch the super-secret defense shuttle to rescue the astronauts trapped at the space station and risk national security or let them die.

Four days after the Democratic convention, Josh begins to staff up the Santos campaign. With Santos and Leo effectively strangers - and Leo not an experienced campaigner - adjustments of roles and responsibilities are required in order to deliver a strong and consistent message. The White House prepares to launch the military Space Shuttle on its rescue mission to the Space Station amidst growing suspicion that proof of its existence was deliberately leaked by someone in the Administration. The Republicans offer Bartlet a concession on an education bill in an attempt to drive a wedge between him and the Santos campaign.

Despite vigorous campaigning, the Santos campaign still struggles to articulate its message and keep the focus on domestic issues rather than gossip and trivia. Although Santos served decades in the military and remains in the reserves, Vinick still appears the stronger candidate on national security issues due to stereotypes about Republicans and Democrats. The White House's decision to halt their own investigation into the leak is a savvy legal move, however it could prove to be costly politically: while Vinick can slam the President for this decision, it's not so easy for Santos to do so. Josh reluctantly recruits help with running the campaign when it becomes obvious that he's trying to do too much himself.

With Santos gaining momentum, the Vinick campaign devises a strategy to catch them off-guard by focusing on immigration issues: by taking a pro-immigration stance, they force Santos to spend time courting the Latino vote. A powerful Christian group is nervous about supporting a Republican presidential candidate who is pro-choice, and demands a guarantee that Vinick only appoint pro-life judges. Vinick hopes that the strong religious credentials of his running mate Sullivan will be enough to satisfy the Christian base, but inevitably finds himself in a difficult situation.

A pro-life special interest group launches an ad attacking Santos for his abortion stance, but Vinick also sees it as trouble since he's also pro-choice and doesn't want to draw attention to the issue. With Vinick ahead in the polls, he has no incentive to debate Santos and thus continues to drag his feet over negotiations. Back at the White House, C.J. orders new Communications Director Will Bailey to not answer questions from the press about the leak investigation.

The Santos campaign's difficulties with the black community continue when a Latino police officer shoots a black child; C.J. offloads preparations for Ellie's wedding to Will when Kate needs her help with Kazakhstan; Josh visits Toby.

President Bartlet's plan to attend his daughter Ellie's White House wedding is jeopardized when Russia and China mobilize troops over growing chaos in Kazakhstan. The Santos campaign has gained ground on Vinick over the last few weeks, but with less than two months until the election it's not clear that the gap can be closed. As Josh obsesses over the electoral math, tracking polls, and decisions on where to spend advertising money, some Democrats are nervous that the election is slipping away, and urge Santos to fire Josh as campaign manager.

Leo's preparation for the Vice Presidential debate is going badly; Santos makes his last trip home before the election; Will and Kate continue to flirt.

A nuclear accident in California sends the White House and both campaigns into overdrive. Meanwhile, China and Russia appear headed for a showdown over elections and oil in Kazakhstan.

The Vinick campaign struggles with the impact of the nuclear accident in California; Josh and Donna have a "moment".

Both candidates face vital choices about which states to campaign in; Vinick tries to put the nuclear issue behind him; Bruno finds Santos's briefcase.

Election day finally arrives; C.J. ponders job offers; the election looks too close to call.

Polls are closing across the country, and the race is too close to call; friends and colleagues react to the news about Leo.

Eyebrows are raised when the President-elect places a call to the president of China and offers a different position than that of Bartlet. Meanwhile, Josh picks his deputy chief of staff.

Santos and his staff prepare for the inauguration as Bartlet and his team look back on their years in the White House.