Which U.S. President, known for his complex relationship with Congress, significantly reshaped the role of the Executive branch during a time of domestic turmoil?

1. He served during a period of intense social change and political polarization.
2. His administration was marked by a significant war, though not as universally agreed on as others.
3. He faced considerable resistance and was even threatened with impeachment.
4. Despite controversy, some of his programs are seen as having laid the groundwork for later civil rights advancements.