President Robert Mugabe has repudiated his Zanu PF negotiators on SADC-facilitated roadmap and reverted to a no-compromise position ahead of a SADC extraordinary summit in Windhoek next week (20 May 2011).

The politburo of his minority Zanu PF party on Tuesday (10 May 2011) resolved to renege on a range of agreements finalised in Cape Town last week and to revert to its December 2010 insistence on elections this year.

The decision is likely to mark the start of increased violence and harassment by Zanu PF militias and Zimbabwe's highly partisan police of members of Morgan Tsvangirai's majority Movement for Democratic Change (MDC-T) and its allied MDC-N.

But it does not spell a complete breakdown of talks by a SADC-mandated South African facilitation, headed by President Jacob Zuma.

Instead it appears to be a negotiating manoeuvre ahead of the SADC summit to strength Mugabe's hand at a forum where he believes he can win more than his Zanu PF negotiators, Justice Minister Patrick Chinamasa and Transport Minister Nicholas Goche, have been able to achieve in talks with the two MDCs.

Mugabe hopes to win back some of the ground he lost on 30 March, when Troika of SADC's Organ on Politics, Defence and Security met in Zambia to demand more rapid progress towards agreement among the three parties in Zimbabwe's inclusive government on a roadmap towards credible elections.

The Troika comprises the previous, current and next chairs of the Organ – Mozambique, Zambia and South Africa – and took its decision based on a report from the SADC-mandated South African facilitators. The Troika also decided to increase SADC's role in Zimbabwe itself, providing for a SADC team based in Zimbabwe to work with the multi-party Joint Monitoring and Implementation Committee (Jomic).

Since the Troika decision, Jomic has made significant progress towards a comprehensive agreement on conditions conducive to a credible election. They met at Cape Town's palatial African Pride Crystal Towers for three days last week (5-7 May) to finalise the agreement.

The Cape Town meeting agreed to disagree on MDC demands for de-pollicisation of Zimbabwe's partisan security forces and to refer this to their principals – Zuma, Mugabe and the heads of the two MDCs. They agreed the meeting should take place within the next fortnight.

On all other substantive matters Zanu PF's negotiators accepted the multi-party consensus:

• Elections will not take place this year. Zanu PF intends to table a proposal on this to the re-scheduled summit, apparently to ensure acceptance of a formulation that avoid the appearance of a climb-down on the election date by Zanu PF.

• Reconstitution of the Zimbabwe Election Commission (ZEC), which has been permanently tainted by its behaviour during 2009 presidential and parliamentary elections. Although Chinamasa and Goche refused to acknowledge ZEC partisanship, arguing that its staff is made up of professional civil servants, they agreed to its reconstitution, with assistance from South Africa's Independent Electoral Commission.

• Expansion of the facilitation team and establishment for a permanent presence in Harare – initially a token presence of three SADC officials to work with Jomic. The facilitation team/SADC office will be set up in Harare after the summit.

• A joint initiative to lobby for the suspension or termination of sanctions imposed by the EU and USA against about 160 Zanu PF figures and a dozen, mainly state-owned, Zimbabwe companies. South Africa failed a fortnight ago to persuade Washington and London – which sets the pace for the EU on Zimbabwe – to lift sanctions as a means of encouraging SADC to go with its more assertive stance on Zimbabwe. Both opted to await the outcome of the summit, but have indicated a willingness to be flexible. A joint South African-Jomic delegation will visit Brussels in June.

The road appeared open to internationally accepted Zimbabwe elections next year – with MDC-T certain to win, under circumstances in which security forces remained neutral.

The Zanu PF politburo decision on Tuesday throws of out all these agreement and takes the facilitators back to the drawing board.

It is based on Mugabe's gamble that he can marshal some support among the SADC heads of state in Windhoek to weaken South Africa's insistence of circumstances essential for free-and-fair elections.

An overwhelming majority of Zanu PF's parliamentary structures have already accepted that elections will only take place in 2012 or 2013, to allow for a referendum on a new constitution and to ensure circumstances are in place to ensure a free and fair election. They have accepted this although it means that Mugabe's availability as Zanu PF's only real electoral drawcard may be unavailable. At 87 his health is failing.

Mugabe has therefore bet heavily on persuading the SADC presidents to compromise, particularly on de-politicisation of the security forces, sufficiently to give his party some prospects of victory in elections.

As things stand, a free and fair election would give the MDCs a 2-to-1 popular vote majority, both in parliament and in the presidential race.

Following the politburo decision, Mugabe sought to further strengthen his position in Windhoek, sending emissaries across Southern Africa to lobby uncommitted SADC members to back him at the summit later this month. Key delegation were headed by hardliner and presidential pretender Defence Minister Emmerson Mnangagwa, who visited lobby President Joseph Kabila in Kinshasa; Goche, fresh from the Cape Town talks, who travelled to meet Botswana's President Ian Khama, recently demonstrating greater warmth towards Mugabe; and State Security Minister Sydney Sekeramayi who travelled to Dar es Salaam.

The politburo announcement, published on Wednesday, is likely to fan the flames of political violence in Zimbabwe. Since news spread last month that elections were unlikely this year, the low intensity violence, intimidation and harassment endemic in much of the country has eased noticeably. Wednesday's announcement is intended to ensure escalation of violence against and harassment of opposition formations while control of security forces is still uncontested.

Violence this year has been sporadic and patchy outside Zimbabwe's cities. In the two Matabeleland provinces and in parts of central Zimbabwe, past war veteran-based violence and harassment is no longer possible. Many veterans have re-joined the revived Zapu – the party of Joshua Nkomo forced to merge with Mugabe's Zanu shortly after independence in 1980 – and are no longer available for Zanu PF harassment of the MDC parties.

Most of the violence, usually, but not solely ignited by Zanu PF, since last December has been in high density, working class suburbs around Harare.

Other, equally effective, forms of harassment likely to escalate in the months ahead include denial of maize seed and fertilizer to small farmers thought to support MDC by agriculture ministry functionaries.