The consensus that conventions are an anachronism, a leftover historical relic that no longer matters, is credible, increasingly widespread—and wrong.

Conventions don’t decide the nominee anymore, but they can be decisive or influential in shaping national politics.

First, conventions can shape or change the trajectory of a presidential race. With Al Gore’s acceptance speech in 2000, he gained 13 to 18 points in the polls, depending on which surveys you believed. By the Saturday after the speech, Gore, who had been double digits behind, was suddenly in the lead. (And I continue to insist that Gore was elected, just not inaugurated, due to the fiat of a Supreme Court that acted like a partisan ward committee.) 

Similarly, four years later, George W. Bush turned his September convention in New York City, just dozens of blocks from Ground Zero, into a vehicle to reinforce vividly his central—indeed, almost his only—message: in the face of a terrorist threat, he was the safest choice to protect America. 

Sometimes, convention moves that look as if they could supercharge a campaign fizzle out afterward. John McCain’s 2008 Hail Mary pass—picking the previously unknown Sarah Palin as his running mate—is a case in point. 

She wowed the delegates and the country in her acceptance address, and McCain took the lead over Barack Obama in polls. However, Palin soon became a liability, a punchline that cast doubt on McCain’s judgment when she spectacularly fumbled basic questions in interview after interview. 

And the fumble can occur at the convention. For example, Mitt Romney’s invitation to Clint Eastwood to speak at the 2012 GOP convention. Eastwood castigated an empty chair standing in for Obama, overshadowing Romney’s remarks that night. 

Two decades earlier, Pat Buchanan’s sulfurous screed on social issues overwhelmed Ronald Reagan’s last appearance at a Republican convention and polluted the first George Bush’s plan to use his week in the sun to reach out and broaden support for his re-election. The look on Barbara Bush’s face as Buchanan thundered his jeremiad was painful—and priceless.

Second, a convention can see a new star emerge or recast the dimensions of the next race. It happened in 1956 when a little-known senator from Massachusetts spoke three times to the Democratic conclave and almost won an open contest for the vice-presidential nomination. Had John F. Kennedy not lost at the end of the roll call, his Catholicism would have been partly blamed for the ticket’s landslide defeat. Instead, he then took a polling lead among Democrats that held until 1960. 

History repeated itself with Obama’s stunning keynote at the 2004 convention. He didn’t lead Hillary Clinton heading into the next presidential campaign, but he had emerged as her most likely rival.

Even well-known leaders can be boosted by a convention in which they do not prevail. Ronald Reagan’s powerful remarks in 1976, unusually delivered at Gerald Ford’s invitation after his acceptance speech, positioned Reagan as the front-runner for the 1980 nomination. Ted Kennedy’s ringing affirmation of Democratic values and the worth of his campaign after his defeat by Jimmy Carter in 1980 had the same effect among Democrats, although he declined to run again.

Third, a convention can signal or speed up major transformations in public policy or national life. Reagan, in 1980, put supply-side cuts at the center of Republican orthodoxy that holds to this day. Kennedy’s successful insistence on a gay rights plank in the 1980 Democratic platform, the first in history in either party, was seen by many as a reach too far; today, that cause is a consensus among Democrats and a majority of Americans. Walter Mondale’s choice of Geraldine Ferraro as his running mate was another first. By 2020, three women were running for president. One of them became vice president and soon may be elected to the highest office in the land.

Conventions are fundamentally about the message. This year, after the assassination attempt on Donald Trump, there was supposed to be a new, “kindler and gentler” Trump who would premier at the GOP convention. Instead, with the selection of JD Vance and Trump’s abrupt decision to abandon the teleprompter during his acceptance speech, he doubled down on the darkness of anger and grievance. 

Now, Kamala Harris and Tim Walz will seek to use their convention as a joyous defense of freedom and democracy and a hopeful summons to a new future. In November, we will learn which message persuaded more Americans—and which convention mattered more.

Read the opposing viewpoint at Counterpoint-the-partys-over-for-political-conventions,159513?.

Robert M. Shrum is the Carmen H. and Louis Warschaw Chair in Practical Politics, a professor of the Practice of Political Science, and the director of the Center for the Political Future and the Unruh Institute of Politics at the Dornsife College of Letters, Arts and Sciences at the University of Southern California. He wrote this for InsideSources.com. Used with permission.