WASHINGTON - Newly empowered congressional Republicans challenged President Obama at both ends of the Capitol on Tuesday, voting in the House to repeal the health-care program he signed into law but faltering in an initial Senate attempt to roll back immigration policies he issued on his own.

There was a third challenge as well, as GOP leaders announced the House would give final approval next week on legislation clearing the way for the Keystone XL pipeline. That would trigger Obama's threatened veto, the first in a new era of divided government.

The skirmishes all seemed likely to end in eventual defeat for Republicans, but served as a potent reminder of their power after Obama challenged them bluntly last month with his State of the Union address and a budget on Monday calling for higher taxes and new spending. The GOP won control of the Senate in last fall's elections, and has its largest House majority in nearly 70 years.

Democrats were defiant. "They're baying at the moon, something that is not going to work," said the party's leader in the House, Rep. Nancy Pelosi, referring to Republicans as the health-care vote neared.

The vote was 239-186 to repeal Obamacare. Similar votes have been held more than 50 times in the four years, but for four freshmen lawmakers from the Philadelphia area, it was their first chance to weigh in.

Reps. Ryan Costello (R., Pa.) and Tom MacArthur (R., N.J.) cast their first votes against Obamacare less than a month into their tenures in Congress. Both had expressed opposition to the law while campaigning.

Costello and MacArthur joined 237 other Republicans in voting for repeal. Three Republicans voted against the repeal (none from the Philadelphia area). It was the 67th time House Republicans had voted to kill or chip away at the Affordable Care Act.

Freshman Reps. Brendan Boyle (D., Pa.) and Donald Norcross (D., N.J.) joined 181 other Democrats in opposing the repeal. No Democrats voted for killing the law.

Across the Capitol, Senate Democrats blocked debate on legislation to fund the Department of Homeland Security and simultaneously overturn presidential executive orders that have spared an estimated four million immigrants in the country illegally from the threat of deportation.

The vote was 51-48, nine shy of the 60 needed to begin work on the measure.

Staff writer Jonathan Tamari contributed to this article.