As the polarization between the two political parties in Congress has increased, the Democrats have become more and the Republicans have become more .

Democrats have become more liberal, and Republicans have become more conservative

Explanation:

Liberal, as the term is understood in the United States, refers to someone who supports socially liberal policies such as minority rights, lgbt rights, and abortion, and at the same time, supports increased government intervention in the economy, for example, more taxation and more spending on social programs.

A conservative, as the term is understood in the United States, refers to someone who supports socially conservative policies such as drug prohibition, religious liberty, and opposition to abortion, and at the same time, supports less government intervention in the economy, for example, lower taxes, and less spending on social programs.

As the political parties have polarized more, the democrats have become more liberal, and the republicans have become more conservative.