Kenya’s presidential race tightened on Friday with frontrunner Uhuru Kenyatta gaining just under half of the ballots counted four days after the vote, raising the prospect of a tense run-off against his main rival Prime Minister Raila Odinga.

Kenyatta, 51, the deputy prime minister who is due to go on trial at The Hague on charges of crimes against humanity linked to the violent aftermath of the last election in 2007, has led since results started trickling in after polls closed on Monday.

Results from strongholds loyal to Odinga, 68, closed some of the gap, but with about a fifth of constituencies still to report, Kenyatta could yet secure more than 50 per cent of  the vote, the level needed for a first-round victory.

The count, questioned by both sides but which international observers broadly said was credible, is likely to go down to the wire. The poll is seen as a critical test for Kenya, East Africa’s largest economy, after its reputation as a stable democracy was damaged by the bloodshed that followed the 2007 election.

Much will rest on whether the final result is accepted, and whether any challenges take place in the courts or on the streets. By 4.00 am ET on Friday, with 9,760,168 total votes tallied, Kenyatta had 4,835,482 votes or 49.5 per cent, to Odinga’s 4,316,005 or 44.2 per cent, according to a display by the electoral commission. That was based on votes reported from 223 of 291 constituencies.

As counting has progressed, Kenyatta’s tally has been nudged above and below the crucial 50 per cent mark. If no candidate achieves more than that level, the top two go to a run-off tentatively set for April.

The Kenyatta and Odinga camps have both raised concerns about the process, so legal battles could dela that, heightening tensions in the divided nation. But this time, both sides have promised to turn to legal channels and keep the peace.