The Important 2020 Senate Elections are less than 2 years away.
These will coincide with the Presidential Election, which will almost certainly feature a Republican Donald Trump running for a second term against a Democratic Party opponent. The election will be bitter and one of the most of the most divisive since the bitter mid-1800's Civil War period.
The Entire U.S. House of Representatives will be up for reelection. Democrats will be seeking to expand upon their majority.
In addition, 34 Senators will be up for reelection. Unlike the 2018 Midterms, more Republicans (22) will be defending their seats than Democrats (12).
It looks like the Senate will break down as 53 Republicans, 47 Democrats (and two independents who vote with Democrats) if two undecided races break to leading candidates (Arizona to D- Kyrsten Sinema and Florida - R to Rick Scott) pending final voting counts.
The party that wins the Presidency controls the Senate in the event of a 50 / 50 split, since the Vice President gets to cast a tie breaking vote.
Which seats right now are the most ripe for pick-up efforts by either party?
Alabama: Doug Jones (D) won a special election against a particularly bad candidate, State Judge Roy Moore, is the #1 Republican target in this very red state. He simply is too progressive for the people of his state.
Michigan: Gary Peters (D) is a supposed target since Michigan narrowly voted for Trump, but Michigan is returning to its Democratic roots, has elected a Democratic Governor in 2018, and Peters is popular in his home state. I do not see him as a viable target.
Arizona Open Seat (R): This is John McCain's seat which will filled by former Republican Senator Jon Kyl who is not running for reelection. Democrats have been doing well in recent years in Arizona. If they carry this state in 2020 they can carry the Senate seat.
Colorado: Cory Gardner (R): Colorado voted for Hillary Clinton and is turning more blue every year. Colorado just put in office Jared Polis as Governor, a Democrat, as America's first LGBT Governor. Cory Gardner is a right wing Republican and will be seriously challenged by a well funded Democratic candidate.
Iowa: Joni Ernst (R): Although Senator Ernst would probably win election today, due to her 51% approval ratings, if Trump ratchets up agricultural tariffs, or if the economy starts to tank, she will find herself open to a challenge in this state that has been known to elect Democratic Senators.
Maine: Susan Collins (R): Collins was once one of the most popular Senators ever elected in her home state, and was lionized by both Democrats and Republicans. However, her deciding vote to confirm Judge Brett Kavanaugh, and some of her other statements which have identified her as a firm member of Mitch McConnell's caucus have left her open to a well-funded challenge among Democrats. Former National Security Advisor Susan Rice is mentioned as one possible candidate.
North Carolina: Thom Tillis (R): If North Carolina votes for a Democratic candidate for President, there is a chance that carry over voting could occur and elect a Democrat here. Tillis won his seat over Democratic Senator Kay Hagan in 2014 by less than 50,000 votes.
Other Senate seats could open up --- if incumbents decide not to run for reelection, or die or resign in office and are replaced by Governors or through other means.
The Democrats do have a shot at taking the Senate chamber in 2020. Few, except for Doug Jones in Alabama, are truly vulnerable.