Lyndon Johnson sought passage of at least a weak civil rights bill in 1957 because he wanted to become president and believed his anti-civil-rights voting record would prevent a Southern candidate from winning the 1960 Democratic nomination.

“Johnson was desperate to make sure that at least some civil rights bill passed that year, even if it was weak. That's because he wanted to become president, but no southerner with his record of consistently voting against civil rights could hope to win the Democratic presidential nomination in 1960.”