This study content analyzed interest group and candidate tweets from the 2020 American presidential election to determine what issues and substantive attributes were most salient on interest group and candidate agendas during the "hot phase" of the campaign. Cross-lagged correlations were conducted during two time periods from Labor Day to Election Day 2020 to measure agenda building effects. These tests were conducted for Democratic nominee and eventual President Joe R. Biden, and Republican nominee and former President Donald J. Trump. These tests were also conducted for two issue-based interest groups: Everytown for Gun Safety and the National Rifle Association. Findings indicate that Biden influenced Trump's campaign agenda, but Trump did not influence Biden's. The interest groups showed reciprocal influence with each other. Given the unprecedented nature of the 2020 election, the candidates were largely talking about the same issues. However, substantive attributes reveal the candidates' true issue agenda. This study offers methodological innovation by utilizing NVivo for content analysis. / Master of Arts / This study examined tweets from 2020 presidential candidates Donald J. Trump and Joseph R. Biden, as well as the National Rifle Association, a gun rights advocacy organization, and Everytown for Gun Safety, a gun control advocacy organization. These tweets were examined from September 7 to November 3, 2020, from Labor Day until Election Day. For the presidential candidates, it was found that although candidates were talking the same general campaign issues, they were using different substantive attributes when speaking of them. The findings also revealed that Biden was successful at influencing Trump's Twitter focus during the examined time period. Tweets from advocacy organizations were tested for presence of gun-related issues. The advocacy organizations spoke about the same issues as the other, but neither group was successful at influencing what the other said. This study highlights the importance of digital political public relations.