Sen. Bernie Sanders shocked no one Sunday morning when he told viewers of CBS's "Face the Nation" that he plans to remain in the presidential race until at least the Democratic convention.

Sanders (Vt.) is certain that he can become the Democratic nominee. But regardless of the outcome, he said he plans to go to the convention and seek what he considers critical changes to the rules. Sanders complained Sunday, as he has many times before, that closed primaries disenfranchise millions of people who may wish to vote for a Democratic candidate. Closed primaries are contests held in states that allow only registered party members, in this case Democrats, to cast ballots.

In April, The Washington Post's Greg Sargent reported that Clinton had outperformed Sanders in states with closed primaries, suggesting that some share of support for Sanders comes from independent voters.

Hillary Clinton’s secret weapon against Bernie Sanders: Democratic voters

This month, that pattern has largely persisted.

Clinton declares victory in Kentucky primary; Sanders wins in Oregon

Sanders may be deeply committed to the cause of overhauling the primary system, but USA Today reported just last week that such changes remain unlikely:

Even if the Vermont senator persuades the Democratic Party to embrace more open primaries in its platform at the party's national convention in July, individual states would have to enact the changes. Experts say that’s unlikely because many state legislatures are completely or partially controlled by Republicans, who have no motive to change the status quo.

On NBC's "Meet the Press," Democratic presidential front-runner Hillary Clinton told host Chuck Todd that Sanders has every right to remain in the race. Clinton said she will be the Democratic nominee for the White House but did not address directly a question about whether Sanders's ongoing campaign has or will damage her ability to beat Donald Trump in a general election.

Both Clinton and Trump are their respective party's likely nominees.