Yields fell after data showed that US consumer spending recorded its biggest increase in more than eight years in September, probably as households in Texas and Florida replaced flood-damaged motor vehicles, but underlying inflation remained muted.

Many investors are seen as reluctant to trade before this week's numerous catalysts, however.

"At the moment, people are cautious; there's not a real great reason to be taking a lot of big positions today," said Thomas Simons, a money market economist at Jefferies in New York. "It is a very busy week, (with) a lot of potentially market-moving events already on the calendar."

Benchmark 10-year notes were last up 12/32 in price to yield 2.39 percent, down from 2.43 percent on Friday.

Other economic releases due this week include manufacturing data on Wednesday and Friday's jobs report for October.

Investors are also waiting to find out who US President Donald Trump will nominate as head of the Federal Reserve.

Trump is leaning toward Fed Governor Jerome Powell, two sources familiar with the matter said on Friday.

Politico reported on Monday that the Fed chair announcement is likely to come on Thursday.

The US central bank is expected to leave interest rates unchanged when it concludes its two-day policy meeting on Wednesday, but investors will be watching for any new indications that a rate hike is likely in December.

The Treasury Department is also due to announce its funding needs for the next two quarters on Wednesday.

Traders will be watching for any new indications that the government may introduce a new long or ultra-long debt maturity as it faces higher funding needs over the coming years.