Ms. Murkowski -– although she will surely run toward the center to differentiate herself from Mr. Miller –- might also have more access than Mr. Crist does to voters on her right. This is because, according to the Public Policy Polling survey, 32 percent of likely Republican voters have an unfavorable impression of Mr. Miller, as do 54 percent of independents. In contrast, only 11 percent of Republicans in Florida have a negative view of Mr. Rubio, according to last month’s Quinnipiac poll.

It is simply not that hard to envision a scenario like the one illustrated below, in which Ms. Murkowski got the votes of about 50 percent of independents, 25 percent of Republicans (mostly those who disliked Mr. Miller), and 35 percent of Democrats (mostly those who thought Mr. McAdams’ candidacy was not viable and were voting tactically). That would get her to about 37 or 38 percent of the vote overall, which could potentially be enough to win depending on how Mr. Miller and Mr. McAdams split the remaining votes.