It seems strange to even write this since, not so long ago, that seemed pretty far-fetched. But now we have had much more public polling and the contours of a 2020 election where Trump is on the ballot and every Republican candidate is tied to him have become clearer. As things stand, that's not a good look for endangered Republican candidates.
"Public polls have shown a huge overlap between voter attitudes in the presidential race between Trump and presumptive Democratic nominee Joe Biden and their preferences in the Senate contest between Kelly and McSally, who lost her Senate bid in 2018 but was then appointed to fill the term of the late GOP Sen. John McCain. Every recent public survey in Arizona has found both Trump and McSally trailing Biden and Kelly, with the Democrat usually leading by even slightly more in the Senate contest than in the presidential race.
"McSally's and Trump's numbers are almost identical," said Mike Noble, a former Republican consultant who now polls for nonpartisan clients in Arizona. "They are so tied together."
These patterns in Arizona are just one measure of a larger trend: Senate elections are becoming more about the party and less about the individual candidates....All signals indicate that "this will be another election in which what people think about Trump determines almost everybody's vote" in Senate contests, says Gary Jacobson, a University of California at San Diego political scientist who specializes in congressional races. "Elections are much more nationalized and partisan."
One high-ranking GOP strategist, who asked for anonymity to discuss changes in the strategic landscape, agreed that very few Senate candidates may be strong enough to swim against the tide of a presidential defeat for their party in their state."
For more info, see the detailed Crystal Ball assessment and Harry Enten's take, both linked to below.