A better-than-expected US non-farm payrolls number, released at 1230 GMT, could soothe concerns about the health of the world's largest economy and fan demand for perceived riskier currencies against the safe haven dollar.
A Reuters consensus forecast showed market players were expecting 113,000 jobs to be added.
"Today if we see a good US number, say above 160,000, that would be bullish for risk and bearish for the dollar," said Daragh Maher, currency strategist at HSBC.
The euro was down 0.1 percent at $1.3003 but held within sight of Thursday's two-week peak of $1.3032. Strategists said there was resistance around $1.3172, the September high. ECB President Mario Draghi said on Thursday that everything was in place for the central bank to buy the bonds of struggling euro zone countries like Spain and that conditions linked to it need not be punitive.
But Draghi, speaking after the ECB left interest rates unchanged at a record low 0.75 percent, offered no clues as to when Spain might make a formal aid request that would activate the programme.
Market players said traders seemed to be looking to sell the euro on rallies but were wary of doing so ahead of a Spanish aid request. If Spain asks for a bailout it would be likely to lift investor appetite to take on risk and boost the euro.
"People who want to go short are looking to do so after a Spanish request for aid triggers a rally in the euro," the trader said, referring to traders who are eager to put on trades against the single currency.
The euro has also been supported by investors buying it back against currencies such as sterling and the Australian dollar, traders said.
The euro eased 0.2 percent against the Australian dollar to A$1.2679 but remained close to a four-month high of A$1.2718 hit on Thursday.