Final answer:
The assertion is true; political parties have become more ideologically polarized, leading to increased influence and power of party leaders within the U.S. House of Representatives.
Step-by-step explanation:
The statement that, as the parties have become more divided, party leaders have grown more powerful, especially in the U.S. House of Representatives, is true.
The past several decades have seen an increase in partisan polarization, with both major political parties, the Democrats and Republicans, becoming more ideologically extreme. As a result, the number of moderates has declined, and party leaders have gained more influence over the legislative process. This has heightened partisanship and made bipartisan cooperation more challenging. The party leadership now plays a significant role in controlling bills and guiding them through the legislative process, using special rules to restrict debate and shape legislative outcomes. These dynamics underscore the increased power of party leaders in a polarized political landscape.