Wallstreet Journal

By JONATHAN WEISMAN

President Obama arrived Monday in Maryland from Afghanistan.

President Barack Obama, after a year of fitfully searching for compromise, is taking a more aggressive tack with his Republican adversaries, hoping to energize Democratic voters and possibly muscle in some Republican support in Congress.

On Thursday, the president challenged Republicans who planned to campaign on repealing his health-care bill with, "Go for it." Two days later, he made 15 senior appointments without Senate consent, including a union lawyer whose nomination had been blocked by a filibuster.

At a bill-signing event Tuesday, he is set to laud passage of higher-education legislation that was approved despite Republican objections through a parliamentary maneuver that neutralized the party's filibuster threat.

On Thursday, Mr. Obama will be in Maine, home state of two moderate Republican senators who opposed his health-care plan, to promote the health law.

Even his surprise trip to Afghanistan on Sunday mobilized the perks of the presidency to marshal public opinion, as pictures were beamed home of Mr. Obama mobbed by U.S. troops.

A senior Democratic official said the push was a textbook case of taking advantage of political momentum as the campaign season begins. Republicans are "on the defensive," the official said, "and as long as they're not cooperating, we ought to keep them there."

Republicans say Mr. Obama's overtures to them have been for show, whether it was his January meeting with House Republicans in Baltimore or last month's televised, bipartisan health-care summit.

The partisanship "may be more visible, and he may be more resolute about it, but as far as most of us are concerned, this is business as usual," said Tennessee Sen. Lamar Alexander, a member of the Republican leadership.

But Mr. Alexander said the recent moves are broader, more public swipes that will hurt the president in the end.

He conceded that Republican leaders have tried to maintain unity in opposition. "When you have 40 Republicans, with your back against the wall and the gallows are right in your face, you're going to do your best to be unified," Mr. Alexander said.

The onus, however, is on the president to build relationships with minority leaders, Mr. Alexander said.

"If you're the president or a governor and you don't have a good relationship with the other party, that's your problem to solve," he said.

Mr. Obama campaigned on calling for an end to partisan bickering in Washington, but once in office he launched an ambitious agenda that pursued several long-held Democratic goals.

Meanwhile, Republicans decided at an early stage to aggressively oppose most of Mr. Obama's agenda. Partisan tensions have run high for most of his term.

Recently, Mr. Obama has been swinging particularly hard. He followed up his "go for it" taunt Thursday with the recess appointment of union lawyer Craig Becker to the National Labor Relations Board, adopting a tactic that presidents of both parties have used in recent decades to skirt the normal confirmation process. Mr. Becker's confirmation had been blocked in the Senate by a filibuster in February.

On Tuesday, Mr. Obama will sign what has been billed as a package of fixes to the health-care bill, approved under rules that required only a simple majority vote to pass in the Senate. That nullified Republicans' power to block it through a filibuster.

Democrats attached to the bill a major overhaul of student-lending laws, which eliminated a federal subsidy for private tuition lenders, federalized most student loans and plowed the savings into expanded federal higher education aid. Republicans say the bill will destroy the private student-lending market.

Mr. Alexander, the Tennessee Republican, called the student-loan move "really brazen" and "the most underreported, biggest Washington takeover in history."

In classic game theory, confrontation is sometimes necessary when cooperation breaks down to present a credible potential threat and get the two sides to re-engage, said Robert Axelrod, a University of Michigan political scientist and author of the game-theory book, "The Evolution of Cooperation." He isn't related to White House senior adviser David Axelrod.

The Senate doesn't work the way game theorists think, said Antonia Ferrier, an aide to Republican Sen. Orrin Hatch of Utah. A body built on personal relationships is likely to spiral into endless tit-for-tat retaliations in the face of Mr. Obama's new turn, she said.

The new tone may be having an impact, though, among some Obama voters who had soured on what they saw as an electric campaigner gone soft.

Republicans are getting "better treatment than they deserve," said Don Miller, 68, a California independent and pipe line consultant who said his support for Mr. Obama was rising.

"He's not a politician yet, but he's learning fast. As he learns to work the Washington establishment he has become more and more effective," said James Shubert, 83, a transportation-services manager in Tennessee.

Robin Moyer, 48, a retired South Carolina school teacher, lamented that the president had been trying to "reach as many people as possible, but sometimes it is overkill."

—Jean Spencer contributed to this article.

Write to Jonathan Weisman at jonathan.weisman@wsj.com