Google Inc. Chief Executive Eric Schmidt will hit the campaign trail this week on behalf of Democratic presidential candidate Barack Obama, signaling Mr. Schmidt's push for a greater voice in politics while giving the Obama campaign a boost from a highly desirable constituency. Mr. Schmidt said his planned endorsement of the Illinois senator is a "natural evolution" from his role as an informal adviser to the Obama campaign. The Google chief plans to join executives from other technology companies to announce their support for Sen. Obama. Sunday, Sen. Obama received an endorsement from Colin Powell, who was President George W. Bush's first secretary of state. Congress is considering measures that could have an adverse impact on Google's business, including laws that could limit companies' ability to deliver personally targeted online advertisements and rules that would allow telecommunications companies to charge different prices for different levels of Internet service. Lawmakers' and regulators' scrutiny of Google, in particular, is intensifying. The company's proposed ad-sharing agreement with Yahoo Inc. triggered a Justice Department probe into whether the deal would give Google too much control over the market and lead to higher prices for online advertisers.