(AP) -- Four U.S. senators want Facebook to make it easier for its more than 400 million users to protect their privacy as the website develops new outlets to share personal information.

The call for simpler privacy controls came in a letter that the senators plan to send Tuesday to Facebook founder . The Associated Press obtained a draft of the letter signed by Sen. Charles Schumer, D-N.Y.; Sen. Michael Bennet, D-Colo; Sen. Mark Begich, D-Alaska; and Sen. Al Franken, D.-Minn.

It marks the second time in the past three days that Schumer has expressed his misgivings about a series of changes that Facebook announced last week. The new features are designed to unlock more of the data that the online hangout has accumulated about people during its six-year history.

Schumer sent a letter Sunday to the calling for regulators to draw up clearer privacy guidelines for Facebook and other Internet social networks to follow.

The political pressure threatens to deter Facebook's efforts to put its stamp on more websites, a goal that could yield more moneymaking opportunities for the privately held company.

Facebook's expansion "raises new concerns for users who want to maintain control over their information," the senators wrote in their preliminary draft.

In a statement late Monday, Facebook spokesman Andrew Noyes said the company wants to meet with Schumer to explain its commitment to privacy.

"We've developed powerful tools to give our users control over what information they want to share, when they want to share it and with whom," Noyes said.

Among other things, Facebook is plugging into other websites so people can communicate their interests with their online entourages. Facebook also tweaked its own website to create more pages where people's biographical information could be exposed to a wider audience.

Before can be shared with other websites, the senators want Facebook to seek users' explicit consent, a process known as "opting in." Facebook currently can share some personal information with websites unless individual users opt out by telling the company they don't want those details to be passed along.

The senators also object to Facebook's decision to allow other businesses store users' data for more than 24 hours.

Zuckerberg, who turns 26 next month, says he just wants to build more online avenues for people to connect with their friends and family. Some of his previous efforts have been detoured by privacy concerns, most notably in 2007 when Facebook users revolted against notification tool, called Beacon, that broadcast their activities on dozens of websites.

responded to that rebellion by giving people more control over Beacon before scrapping the program completely.