With 100 days left until the midterm elections, Democrats have a clear communications advantage over Republicans: they have decided what the election is about, while Republicans have not settled on one unifying story. That is the argument of Lee Hartley Carter, a communications strategist who has spent three decades studying how people make decisions.

The 100-day sprint to the midterms kicks off as Republicans and Democrats clash for control of Congress across the country. Carter, writing about the state of the campaign, says the difference between the two parties is not policy. Republicans have plenty of issues that resonate with voters. The difference is narrative. Voters, he argues, do not carry a mental spreadsheet into the voting booth. They do not compare tax policy, border security, energy production and education reform point by point. Instead, they simplify. They look for one idea that helps them make sense of everything else.

Democrats, Carter says, have given voters that idea by reducing the election to a single word: affordability. Whether their solutions are correct is not the point; from a communications perspective, the message is powerful because it gives voters a lens. Every new headline about rising costs reinforces the same story. That is what strong messaging does. It does not just communicate. It organizes.

Republicans have no shortage of issues that poll well, including immigration. But these remain individual conversations, Carter writes. Collectively, they do not tell one story. The difference is between having a message and having a menu. A message gives people clarity. A menu gives them choices. In persuasion, clarity almost always wins.

The Republican Party's closest thing to a national message is the argument that Democrats have become too extreme, too far left, too ideological and too willing to let government expand into every part of American life. Carter says that message energizes Republicans and persuades some independents. But it starts with Democrats. Affordability starts with voters. Most Americans, he argues, are not waking up asking whether Washington has embraced democratic socialism. They are asking why groceries still cost so much, why buying a home feels out of reach, and why insurance bills, child care costs and monthly budgets remain under pressure.

Democrats, Carter says, have decided that every road leads back to the cost-of-living conversation. Republicans are still asking voters to connect the dots across half a dozen different conversations. That approach may be enough, and it may not. With only 100 days left, the biggest advantage Democrats hold is not necessarily on the issues. It is that they have decided what the election is about. Republicans have not, and in politics, the party that defines the election usually starts with the upper hand.

The next 100 days will not simply determine which party controls the House or Senate. They will determine which story voters carry with them into the voting booth. Elections, Carter argues, are rarely won by the party with the longest list of arguments. They are won by the party that gives people the simplest way to understand the moment they are living through.