If the two Senators do not fall into line with their parties issues, this would be a fascinating election. How would the public respond to a pro-life Democrat or a pro-choice (and pro-LGBTQ rights) Republican?
I think social conservatives would go for Joe. Meanwhile, Collins would gain a great deal of support from college graduates.
The map, in this scenario, would look something like this like this.
310 to 228.
If they both complied more with their party's wishes, it would be something more like this.
283 to 255