Armin Laschet, Chancellor Angela Merkel"s would-be successor, desperately needs his Christian Democrats to win a regional vote on Sunday to avoid questions resurfacing about whether he is the right candidate to lead them into September"s federal election. The sparsely-populated eastern state of Saxony-Anhalt is home to just 2.2 million people, but Sunday"s election has outsized significance as the last regional vote before Germans elect a government for the post-Merkel era on Sept. 26. Surveys in the state show a small lead for the CDU of Laschet and Merkel, but the far-right Alternative for Germany (AfD) is running close behind. "If the AfD wins or even comes close to doing so, that would deeply damage CDU-CSU chancellery candidate Armin Laschet ahead of September," said Naz Masraff at Eurasia, a political consultancy. Merkel, in power since 2005, is stepping down after the federal election, and senior CDU officials concede that it will be tough to retain their party"s appeal to voters after 16 years in charge. National polls show the surging Greens almost tied with the CDU, with both holding around a quarter of the vote. The conservatives picked Laschet in April as their candidate, but only after a tough fight with Markus Soeder, leader of the CDU"s Bavarian sister party and widely seen as a more charismatic choice. The state premier in Saxony-Anhalt, Reiner Haseloff, was among the senior CDU figures who preferred Soeder. Soeder has since lined up firmly behind Laschet and dismissed as "absurd" the idea their alliance could review its choice. But a poor showing in Saxony-Anhalt could reopen the debate. The AfD typically performs better in the former communist east, where the economy is weaker than in the west. Its strength in Saxony-Anhalt has already focused debate on the CDU"s relations with the political right. The "Values Union", a group that says it represents the core of the conservative CDU/CSU bloc, elected a new leader last week, Max Otte, a CDU member who has expressed sympathy for the AfD in the past. Laschet told Deutschlandfunk radio on Tuesday the CDU had nothing to do with the group, and that he would oppose any moves from CDU members to cooperate with the AfD.