Heidi Heitkamp accompanying trump to his tax reform speech

[Famous Mortimer]

To what extent is this a sign that she is willing to vote for a tax reform bill?

She's a smart politician. She knows exactly what to do in order to get reelected, so she takes those steps. This is exactly why the race is Likely D (and closer to Safe than Lean).

No. She's quite stupid. "Tax reform" is one issue where most regular people favor the Democratic position. Of all the issues to win over Republicans, this is the least likely to work.