I'd say that even if there was, that message wouldn't get through. There are many reasons that people vote for one party over another, there's nowhere on a ballot paper to indicate why the vote is being cast.

If you were running a political party, the most logical assumption to make (in the absence of richer feedback) was that the people that voted for you did so because they liked your manifesto and/or believed you'd be more competent than your competition.

With that in mind, an election doesn't really allow any meaningful influence on policy, it has to come in a different form (direct democracy, for example).

I'm not a US citizen, but from what I've read the laws on direct democracy are set at the state level, is that correct? Are there any mechanisms in place to propose policy changes at the federal level (aside from lobby groups in Washington)?

Everyone has an opportunity to vote for more than just a party. There are primary elections where specific candidates with specific policy positions can be selected. Unfortunately, most voters don't bother getting involved with the primaries so we end up with candidates that are selected by the "establishment".

In many states, there is an opportunity for direct democracy to have an effect. Specific initiatives are put on the ballot. In practice, though, specific ballot initiatives are still implemented by the same politicians that tend to bend things to their will anyway.