US Republican presidential candidate Mitt Romney has named conservative Paul Ryan as his running mate in November's election. Mr Ryan, 42, is a congressman for his home state of Wisconsin. Ohio Senator Rob Portman and former Minnesota governor Tim Pawlenty had also been tipped to run with Mr Romney as vice-presidential candidate. The BBC's North America Editor Mark Mardell says the decision is a bold and ideological choice. Recent opinion polls suggest a close race between Mr Romney and President Barack Obama in November's poll, with Mr Obama tending to have a slight lead in most surveys. Analysts say Mr Romney will be hoping to regain momentum in the campaign after a series of pro-Obama campaign advertisements attacking his record.