It has won respect and awards for its street-level reporting of the Arab spring protests, and attracted dedicated audiences in 130 countries, but when it comes to the most lucrative media market of all – the US – al-Jazeera has struggled to make an impact, reaching only a tiny minority of American households.

On Wednesday, the Qatari-based broadcaster signalled its ambition to change that, paying a reported $500m (£300m) for the cable network Current TV, in a deal that could leave Current's co-founder, former US vice-president Al Gore, $100m better off.

Al-Jazeera said it planned to launch a New York-based news channel on the network, likely to be called al-Jazeera America, saying it hoped to "make a positive contribution to the news and information available in and about the United States". The new channel will be separate from the existing al-Jazeera English, which broadcasts from Doha.

For the cash-rich al-Jazeera, which only 4.7 million households in the US can currently watch, the benefits of the purchase are obvious. Though Current TV has struggled to attract significant audiences since its establishment as a liberal news and analysis channel in 2005, its distribution deals give it a potential reach of almost 60 million US homes.

But the Middle Eastern broadcaster, which is owned by the emir of Qatar, faces challenges in its bid to become a mainstream US network, notably a lingering suspicion among viewers and distributors about its Arab origins and political position.

Time Warner Cable Inc, the second biggest US cable company, immediately dropped Current TV on the news of its sale, without commenting on its reasons. Though Time Warner Cable's chief executive, Glenn Britt, said last month that it would take a firmer line on renewing channels with low ratings, some media analysts saw the move as politically motivated.

In a memo to staff on Wednesday, Joel Hyatt, Current TV's co-founder and chief executive, said only that Time Warner "did not consent to the sale to al-Jazeera". He said: "This is unfortunate, but I am confident that al-Jazeera America will earn significant additional carriage in the months and years ahead."

Gore and Hyatt said in a statement: "Current Media was built based on a few key goals: to give voice to those who are not typically heard; to speak truth to power; to provide independent and diverse points of view; and to tell the stories that no one else is telling. Al-Jazeera, like Current, believes that facts and truth lead to a better understanding of the world around us."

The US secretary of state, Hillary Clinton, has praised al-Jazeera's coverage of the Arab spring in the past, saying the network provided "real news".

But despite a campaign urging viewers to press their local distributors to carry al-Jazeera, the channel has until now been unable to extend its reach beyond a few isolated pockets of the US.

Al-Jazeera's director general, Ahmed bin Jassim Al Thani, said of the purchase: "US viewers have clearly demonstrated that they like the way al-Jazeera provides compelling, in-depth news to audiences across the world. Everyone at Al Jazeera takes great pride in the independence, impartiality, professionalism and courage of our journalism. I look forward to bringing these standards to our new American audiences and working with our new colleagues at Current."

Gore and Hyatt have been seeking a buyer for Current TV for some months, amid pitiful ratings that averaged 22,000 households between January and November 2012, despite having 59 million paying subscribers, according to the Wall Street Journal. By comparison, CNN averaged 700,000 households in the same period, and Fox News 1.9 million.

They resisted selling the channel to the rightwing talkshow host Glenn Beck, the Wall Street Journal reported, telling Beck that "the legacy of who the network goes to is important to us and we are sensitive to networks not aligned with our point of view".