By Annika Breidthardt
BERLIN (Reuters) - German Chancellor Angela Merkel's conservatives plunged to their lowest rating in seven months in a leading opinion poll on Sunday as a tax evasion scandal embroiled an ally and their Bavarian sister party faced questions about nepotism.
Support for Merkel's Christian Democrats and Bavarian partner the Christian Social Union fell three percentage points from a week earlier to 37 percent, their lowest ranking since October, the Emnid poll for Bild am Sonntag newspaper showed.
Last month, one of Germany's most admired sports managers, Bayern Munich president Uli Hoeness, said he had voluntarily reported himself to authorities in a tax evasion investigation that exposed Merkel's government to criticism it is lenient on tax cheats.
Hoeness is seen as a supporter of the conservative Bavarian Christian Social Union (CSU) and has had close ties to Merkel.
With five months to go to federal elections and a regional vote in Bavaria, Merkel and CSU leaders have distanced themselves from Hoeness, though the party has also faced questions about the conduct of its own members.
The CSU regional parliamentary floor leader stepped down late last month, saying he had used state funds to pay his wife a hefty salary for working for him, a legal loophole Bavarian lawmakers had used for years.
Some ministers in the regional cabinet have now said they will donate the money they paid their family members to charity.
"There have been a range of events recently that have shattered peoples' trust in the economic elites," said Emnid chief Klaus-Peter Schoeppner. Those events included the Hoeness case and the Bavarian scandal, he added.
The CDU/CSU's junior coalition partner in the federal parliament, the Free Democrats, rose one point in the poll to 5 percent, which would allow them to enter parliament.
Their combined 42 percent put them on par with the joint force of the opposition Social Democrats (SPD), which was unchanged at 27 percent, and the Greens, who gained a point after announcing a divisive "soak-the-rich" campaign for new taxes last week.
Taxes are set to become a hot topic in the run-up to the September 22 election, when Merkel will seek her third term in office.
On Sunday, Bild am Sonntag newspaper reported a CSU lawmaker in the federal lower house had said he had employed his former fiancée and had asked the president of the house, the Bundestag, to check if that broke any rules.
Spiegel magazine reported Bayern Munich's big sponsors, Adidas, Audi, Volkswagen and Deutsche Telekom, wanted Hoeness to suspend his club presidency after the team's Champions League final at the end of May.
The magazine said the sponsors agreed Hoeness could take up office again if he did not have to go to jail. Adidas and Audi have an 18.2 percent stake in Bayern Munich.
(Reporting by Annika Breidthardt; Editing by Andrew Heavens)