Harris appoints her running mate today Trump's biggest mistake yet? JD Vance

Alarm bells are ringing in the Trump campaign: In just three weeks, the political winds have shifted 180 degrees. With Kamala Harris' candidacy at the latest, it is clear that the choice of "JD" Vance was the wrong one.

It was exactly three weeks ago today. Donald Trump is flying high after US President Joe Biden embarrassed himself in a TV duel and Trump then survived an assassination attempt, resulting in an iconic photo.

The New Yorker believes he is on the road to victory, as the polls seem to confirm. Who will the 78-year-old now choose as his designated running mate? Perhaps his former internal party rival Nikki Haley from South Carolina in order to appeal to the female electorate, which has not exactly been in favor of Trump so far?

Or the black senator Tim Scott? Nikki Haley made him great in South Carolina before he publicly spoke out in favor of Trump during the Republican nomination - with a reason that sticks. Or Marco Rubio from Florida, with whom the large Spanish-speaking electorate could be won over?

Exactly three weeks ago, Trump is apparently certain of his victory. On Monday, July 15, he announced on his Truth Social platform that he had chosen Marine veteran James David "JD" Vance from Ohio, the 40-year-old investor and author of the book "Hillbilly Elegy", which is popular with conservatives.

Trump and Vance: Double MAGA Trump

Three weeks later, the political landscape in Washington is completely different. Today, August 5, the opposing party is expected to announce who their running mate is. However, it is not Joe Biden who is choosing a potential deputy, but his former running mate: Donald Trump has to run against Kamala Harris.

This poses various problems for his campaign, but perhaps the biggest is the choice of his running mate. Without necessity, Donald Trump has chosen a man who only scores points in the camp where his boss is unbeatable anyway: the MAGA community. The young, white, staunch conservative is - relatively - well received by them.

Away from this polarized group, however, James David Vance repels many. His strict views on abortion are not only an issue among the female electorate, but also his portrayal of women without children as "childless cat ladies". Polls show that Vance has not been well received by the people so far.

Trump could still get away with it against Biden

Now a runner-up is not the deciding factor in the US presidential election - even Vance herself says. "Even if it hits my ego, my attitude is that it's not important," he admits in an interview. "People are going to vote for Donald Trump and Kamala Harris above all else. That's how these things go."

But it's not quite that simple. Three weeks ago, Trump could still afford to get Vance on board - because it was against Joe Biden. His party has surprisingly good poll ratings among the black population, Hispanics and young people, which is also due to the old white man in the White House.

But now the Republicans are facing a candidate of color with Asian roots who is likely to shake Trump's standing with the above-mentioned voter groups. This is not least due to Trump himself, who has just got himself into hot water with racist remarks about Harris in front of black journalists.

The only tangible measurable effect of the running mates

At the same time, Harris is already standing out in such a way from her still-leader Biden that new opportunities are also opening up for independent voters and the relatively numerous double haters to date who did not want to vote for either the incumbent or Trump. The other side has no chance here with its double MAGA Trump.

When it comes to concretely measurable results of a running mate, there is only one number, CNN knows: the value that the presidential candidate gains in the state from which his running mate comes. It is therefore 0.5 to 2 percentage points. That sounds like nothing, but it can mean the world.

This is due to the electoral system in the USA: most states are firmly in the hands of one party. A certain basic level of electoral support is therefore established. The swing states decide who reaches the required 270 electoral votes and moves into the White House. In these swing states, the odds are sometimes 50-50.

Swing states firmly in view: Who is ahead in Harris

So one percentage point can make the difference between victory and defeat - and in a state like Pennsylvania, 19 electoral votes are at stake. There is a good chance that the election will be decided there, according to CNN: Biden won by a wafer-thin margin of 1.17 percent in 2020. So it's no wonder that Pennsylvania's Democratic governor Josh Shapiro is at the top of the bookmakers' list when it comes to Harris' running mate.

Shapiro is a strong candidate with Jewish roots: he won Pennsylvania by 15 points in 2022 and is very popular there with a 61% approval rating. Candidate Mark Kelly also comes from a swing state, Arizona, whose eleven electoral votes for Biden only came about thanks to a lead of 0.3 percent.

The third contender for Harris' running mate is Tim Walz from swing state Minnesota, who Biden won by more than seven points in 2020. That's almost like knocking down open doors.

With Trump, however, this fits in with his approach: His running mate Vance comes from Ohio, where the Republicans were a whopping eight percentage points ahead of the Democrats in 2020 with their running mate Mike Pence from Indiana. The decision made three weeks ago could still cost the 78-year-old dearly.