BERLIN (Reuters) - Praise for Angela Merkel's tough negotiating skills in forcing through a deal on European budget rules has given way to warnings that the chancellor risks using up her political credit among Germans.
Britain's rejection of last week's agreement, backed by the EU's other 26 leaders, gave Merkel respite from foreign media caricatures casting her as a Kaiser or Fuehrer intent on dominating Europe.
But she won only fleeting relief, as U.S. magazine Newsweek brought out a cover warning: "Achtung! It's Angela!"
While mainland Europe looks aghast at Britain's growing euroscepticism, polls suggest Germans are growing weary of the euro zone and are less impressed by their chancellor's crisis management than post-summit headlines first suggested.
Even her allies warned Merkel not to assume easy passage of decisions taken at the summit, such as handing over some budget sovereignty to Brussels and moving up the launch of the euro zone's permanent bailout mechanism by a year, to mid-2012.
"The Bundestag (parliament's lower house) will study whether constitutional problems could arise from the EU Commission or a European currency commissar intervening directly in national budgets and parliament's control of the budget," said Bundestag speaker Norbert Lammert from Merkel's Christian Democrats.
In a country whose Constitutional Court subjects such things to close scrutiny, Lammert called it "very ambitious" to expect parliament to approve the new bailout fund, or European Stability Mechanism, fast enough to bring it into effect a whole year ahead of schedule.
Always focused on domestic politics, especially with 2013 national elections approaching, Merkel knew she would win points for sticking to her guns on the independence of the European Central Bank and rejecting jointly-issued euro zone bonds.
"When politicians do what they said they would, it's always good for their credibility, which is what happened here," said Joachim Koschnicke of pollsters Forsa.
But the failure of the summit to come up with rapid, drastic solutions to the debt crisis to convince the markets, which have sold the euro and European stocks again this week, sparked talk of the need for yet another summit before the end of the year.
With newspaper front pages describing the German public as running out of patience with the euro zone, a poll by Emnid suggested people are divided over whether the EU is still the best option for Germany. It showed 46 percent believed they would be better off without it, while 45 percent disagreed.
In a Dimap poll for public broadcaster ARD, over half voiced dissatisfaction with Merkel's management of the euro crisis.
Wolfgang Bosbach, a veteran CDU member of parliament who rebelled against Merkel in a cliffhanger vote in September on the current bailout mechanism, promised to check "the small print" very closely in the EU treaty changes.
Bosbach is one of the founders of the "Berlin Circle", a new current in the CDU which wants to renew debate about whether the party has strayed too far from its conservative roots.
CDU leaders like Secretary General Hermann Groehe criticise the group, saying "it's not enough just to propose being more conservative".
Having neither the power nor the inclination to split the party, the group wants internal debate ahead of 2013 when the chancellor is expected to seek a third term.
"You don't leave the family, even when you are angry with 'Mutti' (Mum) about some issues," said Bosbach, using Merkel's nickname in the party. Such tact did not prevent conservative daily Die Welt calling it a new "anti-Merkel group in the CDU".
"Voices saying 'no' to Merkel for a third term have been growing in recent months, and Germans' view of her fluctuates from week to week depending on how negotiations evolve," said Gero Neugebauer, politics professor at Berlin's Free University.
Merkel's Free Democrat coalition allies are openly split on Europe, with a vote among party members on the ESM ending on Tuesday, and the results due out on Friday.
The vote proposed by eurosceptics in the FDP is unlikely to muster the quorum of about 21,500 members needed to make it binding for the party's weak leadership -- in itself an indication of FDP indifference, at best, to the euro's fate.
Merkel knows that such lethargy could turn to hostility were she to heed international and market pressure for more drastic euro crisis "silver bullets" like euro bonds, which the CDU's Bavarian sister party, the CSU, also rejects.
CSU party chief Horst Seehofer signalled that Merkel had taken Germany's negotiating position up to the wire last week and should beware of going any further.
"We would be against treaty changes that hand over national sovereignty, for example in budget law," said Seehofer.
But Merkel biographer Gerd Langguth, a political scientist at Bonn University, said that while Merkel's summit strategy had been risky, with the danger of miring the EU in a lengthy treaty change process, she should get credit for acting decisively, along with her finance minister Wolfgang Schaeuble.
"In the end Merkel will earn points with the Germans because she's the only one besides Schaeuble who has acted, and can act, with authority on this issue," said Langguth.
Additional reporting by Brian Rohan; Writing by Stephen Brown, Editing by Mark Trevelyan