Chancellor since 2005, Germany's first female leader and its first of either sex from the former communist east, remains the unchallenged queen of the Christian Democratic Union (CDU) party.
But after a rocky second term so far, whether Merkel remains secure depends on how the CDU fares in 2011's "super election year" when six of Germany's 16 states go to the polls.
In May, the CDU got a taste of voter unhappiness when it lost power in the most populous state, North Rhine-Westphalia, costing the coalition its majority in the federal upper house.
"She has lost a lot of credit," political scientist Gero Neugebauer told AFP ahead of the party congress in Karlsruhe, southwest Germany, which runs until Tuesday.
The 56-year-old physicist is expected to be re-elected unopposed as party leader on Monday evening but observers will be looking closely at her share of the vote for any sign of discontent. Last time she had almost 95 percent.
"All in all, the actions of her government are viewed negatively by the population at large, and the CDU is slowly starting to distance itself from Mrs. Merkel," Neugebauer said.
In the wealthy state where the party is holding its congress, Baden-Wuerttemberg, the most important of the 2011 elections, the CDU could find itself turfed out of power for the first time since 1952.
If so, this will be due in large part to fierce local opposition to a rail project that has been backed by Merkel. But there are not only local issues at play, both in Baden-Württemberg and further afield.
Merkel won a second term in September 2009 and killed off an unhappy "grand coalition" with the centre-left Social Democrats (SPD) in favour of what she called her "dream coalition" with the Free Democrats (FDP).
But at times, it has seemed more like a nightmare.
Merkel and Wolfgang Schäuble, finance minister, have fought hard to resist calls from the FDP - and from abroad - for tax cuts to boost the economy, preferring instead to reduce Germany's budget deficit by cutting spending.
The coalition partners have also fallen out over a range of issues like healthcare reform, social security and military service, allowing the opposition - particularly the ecologist Greens - to gather support.
The eurozone debt crisis earlier this year also dented Merkel's popularity, leaving her accused of sending German taxpayers' money to bail out "lazy" Greeks with what daily Bild called "the fattest cheque in history."
Meanwhile there has been an exodus of top conservatives including president Horst Koehler over an interview gaffe. There is even speculation that Schäuble, her right hand man, might resign for health reasons.
The government's decision to postpone when Germany abandons nuclear power has sparked mass protests, most recently over a radioactive waste shipment that needed a 20,000-strong police escort to reach its destination.
The result has been falling poll ratings for the coalition, particularly for the FDP, but Merkel expressed confidence on Sunday that things will get better, blaming the unpopularity on the financial crisis and "uncomfortable" decisions.
"At the end of the day the success of our policies will win many people over," Merkel told the Welt am Sonntag newspaper.