Using a regression discontinuity design in a sample of U.S. federal special elections, we investigate how donor firms' political wins impact the adaptive responses of their product-market peers in their political activities, with a particular focus on the appointment of politicians to their boardrooms. By analyzing closely contested special elections, we find that when donor firms had donated to a candidate who narrowly won a special election, their peer firms were 41\% more likely to appoint politicians to their boards in the following year than peers of the donor firms that had supported a narrowly defeated candidate. This adaptive response is more pronounced among peer firms facing greater political risks and operating in industries with more intense competition for government sales. Donor firms' political wins also lead peer firms to increase their product differentiation from those donor firms. We interpret these patterns as evidence of a competitive-dynamics mechanism, where peer firms perceive donor firms' political wins as a threat that could disadvantage them in the regulatory environment, prompting them to strengthen their boards with political capital to navigate potential regulatory changes and mitigate perceived risks. Our findings enrich scholarly understandings of corporate political activities and director selections.