"Germany has had four good years," she wrote in a letter mailed to over five million households ahead of Sunday's vote, in which she seeks a third term for her Christian Democratic Union (CDU).
"We have achieved a lot together. I also want the next four years to be good," wrote Merkel, who is dubbed "Mummy" in her country and often called the world's most powerful woman.
"If you want me to keep working as your chancellor, then please give your votes to the CDU on Sunday," said the letter signed "Your Angela Merkel".
Two new polls placed her coalition with the pro-business Free Democrats (FDP) neck-and-neck at 45 to 45 percent with the combined leftist opposition of the Social Democrats (SPD), Greens and far-left Linke.
However, the Linke, which scored nine percent in both polls, has been rejected as a coalition partner by all major parties.
"We should expect a government in which the conservatives are the strongest
political force and Mrs Merkel very likely the chancellor," said political scientist Gero Neugebauer of Berlin's Free University.
The big question is with whom Merkel would end up governing.
A wild card are small parties that have hovered close to the five-percent mark needed for entry into parliament -- especially the new eurosceptic AfD, which scored 4.0 percent in Friday's Forsa institute poll and 4.5 percent in an Allensbach survey.
Merkel's biggest liability are her junior partners the FDP, who were kicked out of Bavaria's state parliament last Sunday but would, according to the two polls, narrowly scrape by nationally with 5.0 or 5.5 percent.
The FDP, in a desperate bid to hold onto power, has urged conservatives to "split" their ballot by casting district votes for the CDU but giving the Free Democrats their second, or party, vote to save the coalition.
Merkel in her letter implored her supporters to do no such thing and avoid what one newspaper dubbed a "blood transfusion" for the struggling FDP.
Should the smaller party crash out, Merkel would have to seek new partners -- most likely her party's traditional rivals the SPD, with whom she ruled in a previous 2005-09 "grand coalition".
For now the two big parties remain in battle mode, seeking to energise their base and win over millions of undecided voters.
Merkel headed to Munich later Friday on the eve of the world-famous Oktoberfest beer festival, days after the CDU's regional sister party scored a huge victory in Bavaria state.
Her challenger, the SPD's Peer Steinbrück, at a Berlin rally Thursday made a spirited call for more social justice and solidarity in Europe as well as a more muscular leadership than what he labelled Merkel's "going around in circles".
The self-styled "straight talk" candidate has suffered through a series of gaffes and blunders, not helped by a magazine cover photo that showed him giving the middle finger as a non-verbal reply to a question on his limping candidacy.
The image heightened the contrast between brash Steinbrück and what has been called the sphynx-like persona of Merkel, who often sits out problems and avoids polarising language.
The chancellor's campaign trail symbol -- used in a giant placard at Berlin railway station -- is the diamond gesture she makes with her index fingers and thumbs in many photos.
One supermarket chain Friday took out a full-page newspaper advertisement showing a mock ballot paper with pictures of two hand gestures -- one making
the diamond, the other flipping the bird.
"If in doubt," it said, "choose the diamond."
Neugebauer criticised what is widely seen as a shallow campaign focused on symbols not substance.
"There is no discussion about big problems, such as the social split in German society or the problems that exist in Europe," he said.
"When you look at the election campaign, and the likelihood of a grand coalition, you have to conclude that the political culture in Germany has pretty much gone to the dogs."
At Friday's rally in Munich, capital of Germany's conservative heartland Bavaria, Merkel's supporters had no such worries.
"Of course you can criticise and complain about a lot of things but until now, there's been nobody who's done it better than her," said retired shopkeeper Heidmarie Wolf.