The two major American political parties don't just disagree on the issues; they are often fighting on completely different terms and with completely different sets of priorities.

And their shifting priorities tell us almost as much about politics today as do their issue positions.

Case in point: A New Pew Research Center poll shows that, while 80 percent of Republicans see reducing the budget deficit as a priority, just 49 percent of Democrats agree.

Back in 2006, though, when George W. Bush was in the White House, it was Democrats who thought reducing the budget deficit was more important than Republicans, and by a similarly huge margin — 64-36.

Here's another way to look at it:

1) Just 32 percent of today's Republican Party says helping the poor and needy is a top priority, but that number peaked close to 50 percent in recent years, including hitting 46 percent just last year. Sixty-four percent of Democrats say that issue should be a priority.

2) Just 32 percent of today's Democrats say the country should deal with a "moral breakdown." Back in the mid-2000s, that number also peaked near 50 percent. For Republicans, the number who say the "moral breakdown" should be a top priority has constantly been right around 50 percent.

What other big shifts can you find? We encourage everyone to play with the great graphic below — particularly the slider at the top where you can examine the same poll for every year since 2002.