While I disagree with the strong form of Aumann's agreement theorem, by the time we're talking a state senatorial position, you probably should be exchanging enough information with everyone responsible for your party's position as to at least reduce any gaps. There are possible stable orbits outside of complete agreement, but the mechanic involved for state senators favors strong agreement.

Also, folk often conflate the position of individual politicians with the positions of their party just as the reverse, so it kinda is meaningful in that setting, as well.

This is different from the actual populace of the entire nation agreeing with you, since:

• Much of the population doesn't vote at all.
• A non-trivial amount of those voting do so based on erroneous information or no information at all.
• The political alignment of a party changes drastically from location to location.
• The relevant political topics changes depending on position, due to federalism.