Members of Congress gather at the Capitol to observe the anniversary of the Sept. 11, 2001, attacks in Washington. AP

Stuart Rothenberg, Tribune News Service

Increased concern about the likelihood of an economic slowdown, new questions about President Donald Trump’s standing with voters and a special election in Georgia certainly give Democrats some reason for optimism about next year’s fight for the Senate.

But while the Senate map surely is better for Democrats in 2020 than it was last cycle, the party will need an upset or two to win control of the chamber next November. The national dynamic looks to be a problem for the president’s party. An Aug.11-13 Fox News poll had Trump’s job rating at 43% approve/56% disapprove. The Democratic Party had a net favorable of 6 points (51% favorable/45% unfavorable), while the GOP had a net unfavorable of 13 points (41% favorable/54% unfavorable).

Trump’s personal rating was 42% favorable/56% unfavorable, while former President Barack Obama’s personal rating was a much stronger 60% favorable/37% unfavorable. These are national ratings, of course, but they could well reflect similar changes in crucial states with competitive Senate races next year.

In fact, a series of state polls conducted online for Morning Consult showed the president’s job approval in July well below his vote in the 2016 election in Michigan, Wisconsin, Pennsylvania, Iowa and even Ohio.

Colorado remains the biggest headache for the GOP, even though incumbent Cory Gardner is a skilled campaigner who continues to position himself as an “independent.” That message worked with Obama in the White House, but it’s a much harder sell after four years of Trump.

Like his Republican Senate colleagues, Gardner has not been very critical of Trump in a state that looks increasingly blue. Former Gov. John Hickenlooper’s entry into the race adds to Gardner’s problems, though Democrats were already pretty well positioned before Hickenlooper switched contests.

If the 2020 elections are mostly “about Trump,” as I expect, Gardner faces an uphill battle in his bid for a second term. Mark Kelly’s entry into the Arizona race was good news for Democrats, who are trying to defeat Republican Martha McSally for the second election in a row.

McSally’s narrow loss to Democrat Kyrsten Sinema in 2018 demonstrated both the Republican’s assets and liabilities in a state that appears to be inching toward the Democrats. Trump carried the state by about 3.5 points in 2016, but the state’s sprawling suburban areas and minority voters are obvious targets for Democrats next year. Kelly needs to demonstrate that he has the focus and campaign skills to keep up with McSally, who is adept at earning positive media coverage. If he does that, the race has all the markings of a toss-up.

Democrats are notably upbeat about their prospects in North Carolina, where freshman Republican Thom Tillis is seeking a second term. Trump carried the state by just over 3.5 points, while Tillis won his 2014 race by 2 points during Obama’s second midterm election.

Democrats face a competitive primary between state Sen. Erica Smith, Mecklenburg County Commissioner Trevor Fuller and former state Sen. Cal Cunningham. Cunningham, who is white, is the early favorite for the Democratic nomination. Both Smith and Fuller are black.

For Democrats, the key to the race probably boils down to turnout of black and younger voters, as well as whether Cunningham (assuming he is his party’s nominee) can make gains among suburban white voters turned off by Trump’s agenda and personal style.

Inside Elections with Nathan L. Gonzales now rates the race ‹Tilts Republican.’

But even if Democrats sweep Colorado, Arizona and North Carolina, they are likely to need a fourth seat, since the party is unlikely to hold Doug Jones’s Alabama seat. Maine is an obvious Democratic target. Hillary Clinton carried the state in 2016, and Republican incumbent Susan Collins’s vote to confirm Brett Kavanaugh for the Supreme Court rattled abortion rights supporters who have backed her in the past.

But even veteran Democratic strategists acknowledge Collins has built up plenty of goodwill in the relatively small state, where personal relationships matter. Still, the likely Democratic nominee, state House Speaker Sara Gideon, is a credible challenger.

Of course, the likely runoff in the special election “jungle primary” (if no candidate receives more than 50% of the vote in the first election) could create specific circumstances that could benefit one party or the other.

The Senate landscape hasn’t shifted dramatically, but the small change benefits Democrats. They currently have about a 4-in-10 chance to net at least three seats and win the presidency.

Growing Democratic strength and Trump’s weakness in the suburbs, combined with stronger Democratic turnout (compared to 2016) and some Trump fatigue even among Republicans should make the fight for Senate control in 2020 increasingly interesting.