German Chancellor Angela Merkel today said she plans to serve another full four-year term, despite growing criticism within her conservative ranks of the sweeping concessions she made to hold onto power. The veteran leader said that despite the sniping over a poor election result and the loss of key ministries in a fresh coalition deal, she felt no loss of authority and wanted to stay at the helm of Europe's biggest economy until 2021. "I understand the disappointment," she said, but stressed that she "naturally" planned to stick with her pledge to stay on for another four years, rather than make way for a successor before the end of the term. "I am a person who keeps what they have promised," she told public broadcaster ZDF. Merkel won September elections but fell short of a clear majority, in large part due to the rise of the far-right, anti-immigration AfD which took votes away from all major parties. After a gruelling marathon of negotiations, she managed on Wednesday to forge another "grand coalition" deal with the centre-left Social Democrats (SPD), who however extracted a high price. The SPD snatched the powerful finance, foreign and labour ministries, as well as justice and environment, while Merkel's Bavarian allies the CSU took the interior ministry. Handing over the finance ministry - long the domain of Merkel lieutenant and fiscal hawk Wolfgang Schaeuble - "was one concession too many," fumed lawmaker Wolfgang Bosbach, reflecting a widely held view in the Christian Democratic Union (CDU). Facing growing unrest from within her long-obedient CDU, party chief Merkel chose to defend the coalition deal, which must still be approved in an SPD party vote. Losing the finance ministry was "painful", she conceded, but she stressed that the move was "acceptable", since the alternative would have been a breakdown in talks, and likely snap elections. In a nod to party critics who want to see a new generation enter the top ranks, she said that her next cabinet should not only include "the over-60-year-old but also younger" conservative politicians and cover "the full breadth" of opinion in the CDU.