The US Senate has 100 seats, 2 for each state. Senators serve for 6 years with 1/3 up for re-election every two years. However, special circumstances can cause additional elections for partial terms, so this year, 35 Senate seats have elections. Of these 35 seats, 21 are held by Republicans and 14 by Democrats. Certain seats are considered safe for the incumbents running for re-election. This year, it is generally agreed that 15 Republican and 9 Democratic incumbents are considered safe, leaving 6 Republican and 5 Democratic seats in play.

As of September 25, 2022, the fivethirtyeight and Cook Political Reports websites offer these predictions on the 11 seats in play:

                                                                                                                                          538
                                                                                                           Cook               Incumbent
Seat                      Incumbent                           Opponent           Rating                   Win %

Georgia               Warnock (D)                         Walker (R)           Toss-Up                    53
Nevada               Cortez Masto (D)                  Laxalt (R)            Toss-Up                    54       
Wisconsin           Johnson (R)                           Barnes (D)          Toss-Up                    61
No. Carolina      R-Open/Budd(R)                   Beasley (D)         Lean R                      63
Ohio                    R-Open/Vance (R)                Ryan (D)              Lean R                      72

Arizona               Kelly (D)                                 Masters (D)        Lean D                      81
Pennsylvania     R-Open
                            Fetterman (D)                       Oz (R)                  Lean D                      82
Florida                Rubio (R)                               Demings (D)       Lean R                      86       
New Hampshire Hassan (D)                          Baldoc (R)           Lean D                      87
Colorado            Bennet (D)                            O’Dea  (R)           Lean D                      92

Utah                    Lee (R)                                   McMullin (I)       Lean R                      93

We see that 8 incumbents are running for re-election, and all are favored to win by 538. The 3 open seats were held by retiring Republicans, and 2 of the 3 are favored to remain Republican. So if the only seat that changes hands is Pennsylvania, Democrats will have a 51-49 majority in the next Congress.

However, the Cook Political Report and 538 agree on the 3 most vulnerable incumbents, 2 Democrats and 1 Republican. If those 2 Democrats lose and everything else remains as predicted, the Republicans would have a 51-49 majority. So, if you are looking to support a Democratic majority in the Senate, this table gives you considerable focus on which seats currently have the closest races. You can support your favorites with money, or with time (phone banking or letter writing).

Here are links to the campaigns of the Democrats listed above:

https://warnockforgeorgia.com/              https://catherinecortezmasto.com/     https://mandelabarnes.com/                            https://cheribeasley.com/

https://timforoh.com/                                https://markkelly.com/                           https://johnfetterman.com/                              https://valdemings.com/

https://maggiehassan.com/                      https://michaelbennet.com/  

             Sources: https://www.cookpolitical.com/ratings/senate-race-ratings , https://projects.fivethirtyeight.com/2022-election-forecast/senate/