The Republican Party has made significant gains in the US mid-term elections, gaining control of the US Senate, the upper chamber of the US Congress previously controlled by the Democrats.

The Republicans also increased their control of the House of Representatives, the lower chamber, by at least 12 seats in the polls.

Millions headed to the polling stations on Tuesday to elect 36 senators, 36 governors and all 435 members of the House of Representatives.

In press conference on Wednesday, Obama promised to work with his Republican opponents and asked them to back his battles against Ebola and the Islamic State of Iraq and the Levant (ISIL) fighters in Iraq and Syria.

"First, I have submitted a request to Congress for funding to ensure that our doctors, scientists, and troops have the resources that they need to combat the spread of Ebola in Africa and to increase our preparedness for any future cases here at home," Obama said.

That request is for more than $6 billion in emergency funding to fight the deadly epidemic.

"Second, I'm going to begin engaging Congress over a new authorisation to use military force against ISIL," he said.

Maricruz Magowan, a political and economic analyst, talks to Al Jazeera from Washington DC on elections results

According to first results of the elections, the Republicans now control both chambers of Congress for the first time since 2006, and, therefore, holds an increased legislative power in the final two years of Barack Obama's presidency.

"The Republican victory was slow moving in the beginning, results trickling in giving no real indication of any definite trends emerging," Al Jazeera's Mike Hanna, reporting from Washington DC on Wednesday, said.

"However, the thought that Democrats could hold out under Republican pressure was short-lived as a sudden series of wins saw the Republicans move quickly towards their aim of flipping six Senate seats held by Democratic incumbents."

The victory puts the Republicans in position to shape if not dictate the congressional agenda, and their priorities are likely to focus on the economy and foreign policy, limiting Obama's political power.

Obama invited Democratic and Republican leaders of the US Congress to the White House on Friday to take stock of the new political landscape.

The Republicans picked up at least seven Senate seats to guarantee 52 members of the 100-member chamber, US TV networks said. Before the elections, they had 45 seats.

'Emphatic victory'

The winning margin came when Iowa Republican Joni Ernst was declared the winner over Democrat Bruce Braley and Republican Thom Tillis defeated incumbent Democratic Senator Kay Hagan in North Carolina.

The Republican-majority Senate candidates also picked up Democratic seats in the states of Montana, Colorado, West Virginia, South Dakota and Arkansas.

The Republicans are projected to win at least 12 more seats in the House of Representatives, potentially surpassing their largest majority of the post-World War II era.

Al Jazeera's Lawrence Lee reports on likely US foreign policy changes after Republican victory in elections

"Emboldened by their emphatic victory, the Republicans on Capitol Hill are more likely to demand presidential compromise, than seek it," Al Jazeera's Hanna said.

Separately, Republican governors triumphed in key races on Tuesday in the politically important states of Florida, Michigan and Wisconsin, joining the partisan tide that gave Republicans control of the Senate.

Republicans won the governor's posts in the Democratic strongholds of Massachusetts, Maryland and Obama's home state of Illinois, projections say, according to the Reuters news agency.

The election results are being seen as a referendum on the policies of Obama, and the win for the Republicans will complicate his final two years in office.

While Obama's name is not on the ballot, the campaigns have been influenced by his low job-approval rating, political paralysis in Washington and a US economy that is widely seen as not growing enough to help many in the middle classes.

The Republican surge will force Obama to scale back his legislative agenda and limit his ambitions to either executive actions that do not require legislative approval, or items that might gain bi-partisan support, such as trade agreements and tax reform.

It will also test his ability to compromise with newly empowered political opponents who have been resisting his legislative agenda since he was first elected.

Source: Al Jazeera and agencies