Views expressed in opinion columns are the author’s own.

After Democrat Conor Lamb’s electoral victory in Tuesday night’s special election in Pennsylvania’s 18th district, Democrats have one more reason to be optimistic about the 2018 midterms and 2020 elections. The opposition party already tends to be successful in midterm elections, averaging a gain of two Senate seats and 25 House seats per midterm. Furthermore, with recent wins like the Alabama Senate race and even close losses like the House race in South Carolina, Democrats have seen a large demographic swing in their favor. For these reasons, Democrats see a bright future in the 2018 elections, and look to ride that wave into the 2020 election.

However, while Democrats have reason to be optimistic, they overestimate their potential to taking control of the Senate this midterm election and the electoral advantage of incumbent presidents. The reality is that the challenges they face are greater than most expect.

While Democrats need to only win two more Senate seats to gain a majority in the Senate, they are defending 25 seats, five of which are in states President Trump won by 18 points or more. Republicans only need to defend nine seats — of which only one is in a state Hillary Clinton carried in 2016. At the same time, the Republican Party can focus their funding on those nine races while Democrats have to spread their literal wealth. Even the House’s map is not certain in the slightest for the Democrats, and there is a very reasonable chance the Republicans will maintain control of both houses.

Even if the Democrats do win, they are nominating candidates from a variety of backgrounds in an attempt to reinvigorate and redefine their party. Sometimes candidates like Conor Lamb and Doug Jones are nominated, socially moderate candidates that represent constituents that still struggle with serious issues on race and homosexuality. At the same time their party leadership is trying to engage millennials and minorities. In their expansion of the parameters of the identity of the Democratic Party, they may find that some of their candidates are not as progressive as they would hope.

Looking to 2020, incumbency advantage cannot be overlooked. There are structural advantages to Trump, and removing him from office will most likely require a stronger candidate than Clinton and significantly more funding than 2016.

Democrats should continue to celebrate these recent wins, but they must temper their expectations and focus their resources to make gradual gains over the next two elections. Some Democrats might want to flip previously solid red districts after seeing the results in recent elections, but if Democrats overreach they risk wasting this popularity wave and driving it into the ground.

By focusing on close key House races, Democrats will set themselves up for a successful campaign in 2020. A loss for the Democrats will send a clear message to the country that the party is still out of touch with their constituents and that Trump still has major influence with most of America. Now is not the time to go double or nothing, but to invest carefully and intentionally so they can set themselves up for success in the long term. Only in this way can the Democrats best direct this popularity wave to the most productive outcomes.

Moshe Klein is a senior government and politics major. He can be reached at mosheylklein@gmail.com.