Historically, candidates who raise more money increase their chances of winning significantly. This means the more money Democrats are raking in, the better chance they have at winning a Senate majority.

Take a look at more than 100 Senate races for which there was polling from January to June of the election year since 2006. For those years, I compared how much money the Democratic and Republican candidates ended up raising from individual donors.

Democratic challengers who outraise Republican incumbents do about 20 points better than those who don’t. Likewise, Republican challengers who outraise Democratic incumbents do about 15 points better than those who don’t.

We don’t know the fundraising hauls for all the candidates yet for 2020 to make an updated forecast for each seat, but we can make some general points.

The strong fundraising numbers that have been released is consistent with what other data points are showing. Mainly, Democrats are doing really well nationally right now. You wouldn’t expect Democrats to be pulling in this type of dough if the national environment wasn’t in their favor.

More interestingly, money hasn’t just correlated with success historically. It forecasts it, even beyond what the early polling portrays.

Consider a race that other factors (such as polling and the political lean of state) suggest is tied. In such an election, a Democrat who raises twice as much as a Republican is forecast to win by 3 points. If the Democrat takes in four times as much as the Republican, the Democrat would be forecast to win by 5 points.

Relatively small shifts such as these are major given that many of the now competitive races will likely be determined by just a few points in November.

A perfect example of such a race could be the 2020 Iowa Senate contest. Democrat Theresa Greenfield has a slight advantage in the polls, and she also has a strong national Democratic environment at her back. Republican Sen. Joni Ernst benefits from the power of incumbency and the fact that Iowa leans to the right of the nation. All together, these ingredients suggest the most likely outcome is a dead-even race when voting begins in the fall.

Greenfield, though, has already announced that she’s raised more than $6 million in the last three months, a massive sum for Iowa.

Depending on how much money Ernst takes in, Greenfield’s fundraising could make her the slightest of favorites.

You could easily see this type of scenario playing out across races. Imagine a hypothetical universe in which every Democrat raised twice as much as every Republican, as was about the average in 2018.

Given the current polling and other factors, Democrats would be forecast to win two additional seats in such a setting than they would if the money race were even.

Two seats could make all the difference in Senate control given Democrats’ need for that net pickup of three to four seats.

Obviously, not every Democratic candidate is going to raise double the amount as his or her opponent. Some will raise more and some less. We’ll have to see how much each candidate ends up raising before jumping to too many conclusions.

But for now, it looks good for Democrats.