Final answer:
During the 1980s and 1990s, the NRA shifted its stance to strongly oppose gun control measures, endorsing Republican candidates that supported Second Amendment rights, which intensified the polarization between the Democratic and Republican parties.
Step-by-step explanation:
During the conservative resurgence of the 1980s and 1990s, the National Rifle Association (NRA) underwent a significant shift in its political stance. It became more focused on Second Amendment rights and started to oppose legislation that sought to restrict the sale or distribution of guns and ammunition, highlighting a move away from any form of gun control measures that it had previously supported. This included endorsing and backing candidates that resonated with their stance on gun rights, primarily within the Republican Party, evident from the NRA's grading system for politicians based on their voting records on gun-related issues.
The Democratic Party became more liberal, and the Republicans became more conservative, intensifying the polarization between the two parties. Throughout the 1980s and 1990s, the NRA became a potent conservative interest group, instrumental in the elections, such as influencing the 2000 presidential election against Al Gore, who lost key states partly due to the NRA's campaigning and support for his opponent. Thus, the NRA's alignment with the conservative movement and the Republican Party became more conspicuous during this period.