Do candidates value their ambitions to hold office over their party identifications? This study investigates the effect of intragroup competition on disloyal candidate behavior toward parties using the case of open list proportional representation elections in Brazilian city councils. Using a regression discontinuity design, I find that candidates who fail to secure a seat over their political allies, be them coalition members or copartisans, are more likely to leave their party either by switching affiliation or abandoning candidacy in their municipalities. I also determine that party switching is rooted in opportunistic behavior, where losing candidates leave their party when their personal vote shares are higher. This effect persists even for stronger and more disciplined parties, namely the Workers' Party. Finally, given the strategic fluidity of party affiliation and the electoral opportunism behind party switching, I provide evidence that this nullifies the personal incumbency advantage for city councilors.