Washington: Barack Obama wants to stay relevant until the end of his historic presidency. But the Republicans are in power in Congress, and are determined to show it.

The battle lines were drawn this past week for the final two years of Obama's term, with neither side able to claim the upper hand.

The defiant president used his State of the Union speech to challenge congressional Republicans to raise taxes on the wealthy to give relief to the shrinking middle class. The Republican leader of the House fired back with the highly unusual step of inviting Israel's leader to speak to Congress without consulting the White House.

The Republicans, newly dominant in both houses of Congress, are not going to take the bait on taxes. But Obama is trying to demonstrate he has a key political role to play over the next two years: Bolstering the Democratic Party's chances of holding on the White House in the 2016 election. To that end, Obama is trying to show voters that his party cares for poor and middle class Americans, and the Republicans don't. He also made sure to claim credit for lifting the U.S. out of economic recession, saying his administration proved critics wrong with policies that have brought the "fastest economic growth in over a decade."

The tone of his speech was typical for the president who, far from retreating, has been on the offensive since Republicans dealt the Democrats a crushing defeat in November elections, seizing control of the Senate and expanding their majority in the House.

Obama made history the day he was first elected America's first black president in 2008, and his lofty rhetoric promising both change and bipartisan cooperation raised high hopes among many Americans frustrated with the wars and economic turmoil of George W. Bush's presidency. But Obama has struggled to shore up a clear legacy. The Republicans, who have controlled the House since 2010, have thwarted many of his domestic initiatives. New conflicts abroad have wrong-footed Obama's efforts to live up to the Nobel Peace prize he won less than a year into his presidency.

With even more power now, the Republicans are certain to pursue legislation that would diminish or overturn Obama's signature achievements, including his overhauls of the health care and immigration systems. By the end of the week, Obama had vowed to veto eight measures that the Republican-controlled Congress has drawn up to undo his policies or threaten Democratic priorities. The number of veto threats was all the more notable because Obama has only vetoed legislation twice in six years, the fewest of any president dating back to the 1880s.

The Republicans showed some weakness over the past week. A deep split between moderate Republicans and firebrand conservatives forced the party to retreat from a House bill that would have banned abortion after 20 weeks. They did pass a measure that would permanently block federal money for nearly all abortions, but that was a renewal of a prohibition that has essentially been in effect for decades.

Still, the flashiest attempt to show who's in charge came from the Republicans. Without bothering to ask Obama, House Speaker John Boehner invited Israeli Prime Minister Benjamin Netanyahu to speak to a joint session of Congress in March.

Boehner's act served as a counterpunch to Obama's forceful State of the Union address. The House leader is also trying to bolster the position of those in Congress trying to pass legislation threatening more sanctions on Iran if a deal is not reached on that country's nuclear program. Netanyahu is a vocal critic of the nuclear talks between Iran and six world powers.

Among Obama's eight veto threats: A vow to block any legislation imposing further sanctions on Iran.

The White House declared that Obama would not meet with Netanyahu during the March visit, saying it wanted to avoid the appearance of meddling in Israel's elections. But the announcement gave the impression that Obama was both retaliating against Netanyahu for going along with Boehner's break with tradition, and trying to demonstrate that the House leader cannot dictate White House policy and scheduling.