BERLIN -- Germany's race for Parliament tightened Thursday, three days before elections, with fresh polls underlining the difficulty that even the popular chancellor, Angela Merkel, faces in building a winning coalition.
Ms. Merkel's Social Democratic challenger, Peer Steinbrück, a classic center-leftist who has deep experience in Germany's state and federal governments, urged his party to make the most of what it says is collapsing support for the chancellor and her Christian Democrats.
"In three days, you can be rid of them!" Mr. Steinbrück told a crowd gathered in Alexanderplatz, in the heart of former East Berlin, accusing the Merkel-led coalition of being "the most quarrelsome, useless and backward-looking" government in modern German history.
The chancellor herself, Mr. Steinbrück charged, has given no direction in the past four years. Instead, "she prefers to drive around in circles," like a caged tiger at the Berlin Zoo, he added.
A poll published Thursday showed that Ms. Merkel's center-right party had the support of 38 percent of German voters. Its current coalition partners, the business-minded Free Democrats, had the support of 6 percent, according to the poll, which was conducted by Insa for the newspaper Bild-Zeitung. The Free Democrats could squeak by into Parliament if that support holds at above the 5 percent threshold.
The center-left Social Democrats are backed by 28 percent of voters, and the Greens by 8 percent, the poll found. The far-left Linke, which Mr. Steinbrück has said cannot be partners in government, polled at 9 percent, with the Alternative for Germany, the only party that explicitly rejects the euro, notching 5 percent, which would make it a surprise entry into Parliament. The poll surveyed 2,248 voters by telephone from Sunday to Wednesday and had a margin of sampling error of 3 percentage points, Insa said.
Both major parties, insisting that Germany's future is firmly in Europe, have ruled out any coalition with the Alternative for Germany. If the anti-euro party does get into Parliament, it increases the odds that Ms. Merkel will remain chancellor, but only as the head of a so-called grand coalition with the Social Democrats.
That would match the coalition that governed in her first term, when Mr. Steinbrück was finance minister and the pair together guided Germany through the 2008 financial crisis. And it would potentially make Mr. Steinbrück a key player in the next phase of Germany's leadership, whether his party wins or not.
For his part, Mr. Steinbrück, 66, has said that he will not be part of another grand coalition. But it is increasingly clear that he would like to be part of negotiating whatever program the two big parties can thrash out.
The uncertainty of the outcome means that the European Union, which has been holding its breath as the German vote nears, is likely to wait a few more months before learning where Berlin would like to guide the troubled Continent.
Mr. Steinbrück, a bright but sometimes blustering politician, was regarded as a strong alternative to Ms. Merkel, 59, when he declared his candidacy a year ago.
Almost immediately, however, he started to stumble, first over disclosures that he had received $1.7 million for speeches and writings, then over whether politicians were paid enough, and next over a suggestion that he would never buy cheap wine.
His party, which is still divided over a legacy of labor and welfare reforms that it initiated when last in power under Ms. Merkel's predecessor, Gerhard Schröder, was slow to get its campaign rolling. Even as late as July, Mr. Steinbrück seemed a somewhat reluctant slogger on the trail.
Since his lone television debate with Ms. Merkel on Sept. 1, from which he emerged looking like he could be chancellor, Mr. Steinbrück has taken to campaigning with zest. In a format that is unusual for German election campaigns, which tend to be scripted and repetitive, he has hit the road with a strategy called "plain talk," in which citizens sit around him as he fields their written questions -- filtered through a moderator but not obviously prepared.
Mr. Steinbrück, who once governed Germany's most populous state, North Rhine-Westphalia, is also a passionate chess player and has one of the readier wits on the campaign trail.
"I'll start off answering your questions, and then I think it's a 120-minute election speech and I will read it to make it even more boring," he said, jokingly, as he took the stage one evening in Munich last week, with barely 1,500 supporters shivering through his presentation.
He has regularly accused the news media of writing his political obituary in advance, reminding a television interviewer on Aug. 30 that in soccer, a national passion here, "it's not a matter of the first 20 minutes, but of the last 10" as to who wins. "I am amazed at how many people in your profession have already written their ready commentaries," he added.
Mr. Steinbrück became a national topic of conversation last weekend when the magazine of the Süddeutsche Zeitung newspaper showed him giving his middle finger in reaction to an unseen interviewer who had asked him to respond to unkind nicknames attached to him during the campaign.
The photo dated from July 29, when Mr. Steinbrück was far behind the chancellor in personal popularity polls. He still trails, but by fewer percentage points.
Even Germans who do not share Ms. Merkel's center-right politics say they believe that she has done a good job of guiding the nation to relative prosperity in Europe, handling the euro crisis and reducing unemployment from around five million when she took office to roughly three million now.
Her party, which in the last two elections saw its support drop just ahead of the actual vote, has centered its entire campaign on Ms. Merkel.
Since her Free Democratic partners made a poor showing in Bavarian state elections last Sunday, she has appealed directly to voters, appearing on national television late Wednesday to urge all citizens to use both of their votes -- for election district candidates and for party lists -- for her and the Christian Democrats. That, she is telling Germans, is the only way to guarantee that she stays in charge.
Correction: September 19, 2013, Thursday
This article has been revised to reflect the following correction: An earlier version of this article misquoted remarks by Peer Steinbrück to an audience in Munich last week. He said, jokingly, that he would give a "120-minute election speech," not a "20-minute election speech."
This article originally appeared in The New York Times.